1.
Eosin
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In addition to staining proteins in the cytoplasm, it can be used to stain collagen and muscle fibers for examination under the microscope. Structures that stain readily with eosin are termed eosinophilic, the name Eosin comes from Eos, the Ancient Greek word for dawn and the name of the Ancient Greek goddess of the dawn. There are actually two closely related compounds commonly referred to as eosin. Most often used is Eosin Y, it has a slightly yellowish cast. The other eosin compound is eosin B, it has a faint bluish cast. The two dyes are interchangeable, and the use of one or the other is a matter of preference, Eosin Y is a tetrabromo derivative of fluorescein. Eosin B is a dibromo dinitro derivative of fluorescein, Eosin is most often used as a counterstain to hematoxylin in H&E staining. H&E staining is one of the most commonly used techniques in histology, tissue stained with haematoxylin and eosin shows cytoplasm stained pink-orange and nuclei stained darkly, either blue or purple. Eosin also stains red blood cells intensely red, for staining, eosin Y is typically used in concentrations of 1 to 5 percent weight by volume, dissolved in water or ethanol. For prevention of growth in aqueous solutions, thymol is sometimes added. A small concentration of acetic acid gives a deeper red stain to the tissue. It is listed as an IARC class 3 carcinogen, romanowsky stain Merbromin Jocelyn H. Bruce-Gregorios, M. D. Histopathologic Techniques, JMC Press Inc
2.
Toxoplasma gondii
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Toxoplasma gondii is an obligate intracellular, parasitic alveolate that causes the disease toxoplasmosis. For example, previous estimates have shown the highest prevalence of persons infected to be in France, although mild, flu-like symptoms occasionally occur during the first few weeks following exposure, infection with T. gondii produces no readily observable symptoms in healthy human adults. This asymptomatic state of infection is referred to as a latent infection and has recently been associated with numerous subtle adverse or pathological behavioral alterations in humans, in infants, HIV/AIDS patients, and others with weakened immunity, infection can cause a serious and occasionally fatal illness, toxoplasmosis. T. gondii has been shown to alter the behavior of infected rodents in ways that increase the chances of being preyed upon by felids. Support for this hypothesis stems from studies showing T. gondii-infected rats have a decreased aversion to cat urine. The rats would not shy away from areas where cats live, widespread histone-lysine acetylation in cortical astrocytes appears to be another epigenetic mechanism employed by T. gondii. Differences in aversion to cat urine are observed between non-infected and infected humans and sex differences within these groups were apparent, as well, because T. gondii can sexually reproduce only within cats, they are defined as the definitive host of T. gondii. All other hosts – hosts in which asexual reproduction can occur – are defined as intermediate hosts. When a member of the cat family is infected with T. gondii, inside these intestinal cells, the parasites undergo sexual development and reproduction, producing millions of thick-walled, zygote-containing cysts known as oocysts. Infected epithelial cells eventually rupture and release oocysts into the intestinal lumen, oocysts can then spread to soil, water, food, or anything potentially contaminated with the feces. Highly resilient, oocysts can survive and remain infective for many months in cold, ingestion of oocysts by humans or other warm-blooded animals is one of the common routes of infection. Humans can be exposed to oocysts by, for example, consuming unwashed vegetables or contaminated water, although cats can also be infected by ingesting oocysts, they are much less sensitive to oocyst infection than are intermediate hosts. T. gondii is considered to have three stages of infection, the stage of rapid division, the bradyzoite stage of slow division within tissue cysts. Tissue cysts in tissues such as brain and muscle tissue, form approximately 7–10 days after initial infection, inside host cells, the tachyzoites replicate inside specialized vacuoles created during parasitic entry into the cell. Tachyzoites multiply inside this vacuole until the host cell dies and ruptures, releasing and spreading the tachyzoites via the bloodstream to all organs and tissues of the body, inside host cells, clusters of these bradyzoites are known as tissue cysts. The cyst wall is formed by the vacuole membrane. Although bradyzoite-containing tissue cysts can form in any organ, tissue cysts predominantly form and persist in the brain, the eyes. Cysts usually range in size between five and 50 µm in diameter, consumption of tissue cysts in meat is one of the primary means of T. gondii infection, both for humans and for meat-eating, warm-blooded animals
3.
American and British English spelling differences
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Many of the differences between American and British English date back to a time when spelling standards had not yet developed. For instance, some spellings seen as American today were once used in Britain. But English-language spelling reform has rarely been adopted otherwise, and thus modern English orthography varies somewhat between countries and is far from phonemic in any country, in the early 18th century, English spelling was inconsistent. These differences became noticeable after the publishing of influential dictionaries, todays British English spellings mostly follow Johnsons A Dictionary of the English Language, while many American English spellings follow Websters An American Dictionary of the English Language. Webster was a proponent of English spelling reform for reasons both philological and nationalistic, in A Companion to the American Revolution, John Algeo notes, it is often assumed that characteristically American spellings were invented by Noah Webster. He was very influential in popularizing certain spellings in America, rather he chose already existing options such as center, color and check for the simplicity, analogy or etymology. William Shakespeares first folios, for example, used spellings like center and color as much as centre, Webster did attempt to introduce some reformed spellings, as did the Simplified Spelling Board in the early 20th century, but most were not adopted. In Britain, the influence of those who preferred the Norman spellings of words proved to be decisive, later spelling adjustments in the United Kingdom had little effect on todays American spellings and vice versa. For the most part, the systems of most Commonwealth countries. Australian spelling has also strayed slightly from British spelling, with some American spellings incorporated as standard, New Zealand spelling is almost identical to British spelling, except in the word fiord. There is also an increasing use of macrons in words that originated in Māori, most words ending in an unstressed -our in British English end in -or in American English. Wherever the vowel is unreduced in pronunciation, e. g. contour, velour, paramour and troubadour the spelling is the same everywhere, most words of this kind came from Latin, where the ending was spelled -or. They were first adopted into English from early Old French, after the Norman conquest of England, the ending became -our to match the Old French spelling. The -our ending was not only used in new English borrowings, however, -or was still sometimes found, and the first three folios of Shakespeares plays used both spellings before they were standardised to -our in the Fourth Folio of 1685. After the Renaissance, new borrowings from Latin were taken up with their original -or ending, Websters 1828 dictionary had only -or and is given much of the credit for the adoption of this form in the United States. Johnson, unlike Webster, was not an advocate of spelling reform and he preferred French over Latin spellings because, as he put it, the French generally supplied us. In Jeffersons original draft it is spelled honour, Honor and honour were equally frequent in Britain until the 17th century, honor still is, in the UK, the usual spelling as a persons name and appears in Honor Oak, a district of London. In derivatives and inflected forms of the words, British usage depends on the nature of the suffix used
4.
Staining
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Staining is an auxiliary technique used in microscopy to enhance contrast in the microscopic image. Stains and dyes are used in biology and medicine to highlight structures in biological tissues for viewing. Stains may be used to define and examine bulk tissues, cell populations, in biochemistry it involves adding a class-specific dye to a substrate to qualify or quantify the presence of a specific compound. Staining and fluorescent tagging can serve similar purposes, biological staining is also used to mark cells in flow cytometry, and to flag proteins or nucleic acids in gel electrophoresis. Simple staining is staining with only one stain/dye, there are various kinds of multiple staining, many of which are examples of counterstaining, differential staining, or both, including double staining and triple staining. In vivo staining is the process of dyeing living tissues—in vivo means in life, by causing certain cells or structures to take on contrasting colour, their form or position within a cell or tissue can be readily seen and studied. In vitro staining involves colouring cells or structures that have removed from their biological context. Certain stains are often combined to reveal more details and features than a single stain alone, combined with specific protocols for fixation and sample preparation, scientists and physicians can use these standard techniques as consistent, repeatable diagnostic tools. A counterstain is stain that makes cells or structures more visible, for example, crystal violet stains only Gram-positive bacteria in Gram staining. A safranin counterstain is applied that stains all cells, allowing identification of Gram-negative bacteria, while ex vivo, many cells continue to live and metabolize until they are fixed. Some staining methods are based on this property and those stains excluded by the living cells but taken up by the already dead cells are called vital stains. Those that enter and stain living cells are called supravital stains, however, these stains are eventually toxic to the organism, some more so than others. To achieve desired effects, the stains are used in very dilute solutions ranging from 1,5000 to 1,500000, note that many stains may be used in both living and fixed cells. The preparatory steps involved depend on the type of analysis planned, fixation–which may itself consist of several steps–aims to preserve the shape of the cells or tissue involved as much as possible. Sometimes heat fixation is used to kill, adhere, and alter the specimen so it accepts stains, most chemical fixatives generate chemical bonds between proteins and other substances within the sample, increasing their rigidity. Common fixatives include formaldehyde, ethanol, methanol, and/or picric acid, pieces of tissue may be embedded in paraffin wax to increase their mechanical strength and stability and to make them easier to cut into thin slices. Permeabilization involves treatment of cells with a mild surfactant and this treatment dissolves cell membranes, and allows larger dye molecules into the cells interior. Mounting usually involves attaching the samples to a microscope slide for observation
5.
Histology
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Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. It is commonly performed by examining cells and tissues under a microscope or electron microscope, the specimen having been sectioned, stained. Histological studies may be conducted using tissue culture, where human or animal cells are isolated and maintained in an artificial environment for various research projects. The ability to visualize or differentially identify microscopic structures is frequently enhanced through the use of histological stains, histology is an essential tool of biology and medicine. Trained physicians, frequently licensed pathologists, are the personnel who perform histopathological examination and their field of study is called histotechnology. In the 17th century, Italian Marcello Malpighi invented one of the first microscopes for studying tiny biological entities, Malpighi analysed several parts of the organs of bats, frogs and other animals under the microscope. Malpighi, while studying the structure of the lung, noticed its membranous alveoli and his discovery established how the oxygen we breathe enters the blood stream and serves the body. In the 19th century, histology was a discipline in its own right. The French anatomist Bichat introduced the concept of tissue in anatomy in 1801, the 1906 Nobel Prize in Physiology or Medicine was awarded to histologists Camillo Golgi and Santiago Ramon y Cajal. They had dueling interpretations of the structure of the brain based in differing interpretations of the same images. Cajal won the prize for his theory and Golgi for the staining technique he invented to make it possible. There are four types of animal tissues, muscle tissue, nervous tissue, connective tissue. All tissue types are subtypes of these four basic tissue types and their structure is very different from animal tissues. The most common fixative for light microscopy is 10% neutral buffered formalin, for electron microscopy, the most commonly used fixative is glutaraldehyde, usually as a 2. 5% solution in phosphate buffered saline. These fixatives preserve tissues or cells mainly by irreversibly cross-linking proteins and this can be detrimental to certain histological techniques. Further fixatives are often used for electron microscopy such as osmium tetroxide or uranyl acetate Formalin fixation leads to degradation of mRNA, miRNA and DNA in tissues, however, extraction, amplification and analysis of these nucleic acids from formalin-fixed, paraffin-embedded tissues is possible using appropriate protocols. Frozen section procedure is a way to fix and mount histology sections using a refrigeration device called a cryostat. It is often used after surgical removal of tumors to allow determination of margin
6.
Medical diagnosis
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Medical diagnosis is the process of determining which disease or condition explains a persons symptoms and signs. It is most often referred to as diagnosis with the context being implicit. The information required for diagnosis is typically collected from a history, often, one or more diagnostic procedures, such as diagnostic tests, are also done during the process. Sometimes Posthumous diagnosis is considered a kind of medical diagnosis, Diagnosis is often challenging, because many signs and symptoms are nonspecific. For example, redness of the skin, by itself, is a sign of many disorders, thus differential diagnosis, in which several possible explanations are compared and contrasted, must be performed. This involves the correlation of various pieces of information followed by the recognition and differentiation of patterns, occasionally the process is made easy by a sign or symptom that is pathognomonic. Diagnosis is a component of the procedure of a doctors visit. From the point of view of statistics, the procedure involves classification tests. The first recorded examples of medical diagnosis are found in the writings of Imhotep in ancient Egypt, a Babylonian medical textbook, the Diagnostic Handbook written by Esagil-kin-apli, introduced the use of empiricism, logic and rationality in the diagnosis of an illness or disease. Traditional Chinese Medicine, as described in the Yellow Emperors Inner Canon or Huangdi Neijing, specified four diagnostic methods, inspection, auscultation-olfaction, interrogation, hippocrates was known to make diagnoses by tasting his patients urine and smelling their sweat. This article uses diagnostician as any of these person categories, a diagnostic procedure does not necessarily involve elucidation of the etiology of the diseases or conditions of interest, that is, what caused the disease or condition. Such elucidation can be useful to optimize treatment, further specify the prognosis or prevent recurrence of the disease or condition in the future, the initial task is to detect a medical indication to perform a diagnostic procedure. Indications include, Detection of any deviation from what is known to be normal, such as can be described in terms of, for example, anatomy, physiology, pathology, psychology, a complaint expressed by a patient. The fact that a patient has sought a diagnostician can itself be an indication to perform a diagnostic procedure, even during an already ongoing diagnostic procedure, there can be an indication to perform another, separate, diagnostic procedure for another, potentially concomitant, disease or condition. A diagnostic test is any kind of medical test performed to aid in the diagnosis or detection of disease, Diagnostic tests can also be used to provide prognostic information on people with established disease. Processing of the answers, findings or other results, consultations with other providers and specialists in the field may be sought. There are a number of methods or techniques that can be used in a diagnostic procedure, in reality, a diagnostic procedure may involve components of multiple methods. The final result may also remain a list of possible conditions, the resultant diagnostic opinion by this method can be regarded more or less as a diagnosis of exclusion
7.
Pathology
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Pathology is a significant component of the causal study of disease and a major field in modern medicine and diagnosis. Similarly, a condition is one caused by disease, rather than occurring physiologically. A physician practicing pathology is called a pathologist, as a field of general inquiry and research, pathology addresses four components of disease, cause, mechanisms of development, structural alterations of cells, and the consequences of changes. Further divisions in specialty exist on the basis of the involved sample types, organs, the sense of the word pathology as a synonym of disease or pathosis is very common in health care. The persistence of this usage despite attempted proscription is discussed elsewhere, the study of pathology, including the detailed examination of the body, including dissection and inquiry into specific maladies, dates back to antiquity. Notably, many advances were made in the era of Islam, during which numerous texts of complex pathologies were developed. By the 17th century, the study of microscopy was underway and examination of tissues had led British Royal Society member Robert Hooke to coin the word cell, setting the stage for later germ theory. However, pathology as an area of specialty was not fully developed until the late 19th and early 20th centuries. This realization led to the understanding that diseases are able to replicate themselves. To determine causes of diseases, medical experts used the most common and widely accepted assumptions or symptoms of their times, by the late 1920s to early 1930s pathology was deemed a medical specialty. The modern practice of pathology is divided into a number of subdisciplines within the discrete but deeply interconnected aims of biological research, anatomical pathology is itself divided into subfields, the main divisions being surgical pathology, cytopathology, and forensic pathology. Sometimes, pathologists practice both anatomical and clinical pathology, a known as general pathology. Cytopathology is a branch of pathology that studies and diagnoses diseases on the cellular level, however, cytology samples may be prepared in other ways, including cytocentrifugation. Dermatopathology is a subspecialty of pathology that focuses on the skin. It is unique, in there are two paths a physician can take to obtain the specialization. The completion of this allows one to take a subspecialty board examination. Dermatologists are able to recognize most skin diseases based on their appearances, anatomic distributions, sometimes, however, those criteria do not lead to a conclusive diagnosis, and a skin biopsy is taken to be examined under the microscope using usual histological tests. One of the greatest challenges of dermatopathology is its scope, more than 1500 different disorders of the skin exist, including cutaneous eruptions and neoplasms
8.
Histological section
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Histology is the study of the microscopic anatomy of cells and tissues of plants and animals. It is commonly performed by examining cells and tissues under a microscope or electron microscope, the specimen having been sectioned, stained. Histological studies may be conducted using tissue culture, where human or animal cells are isolated and maintained in an artificial environment for various research projects. The ability to visualize or differentially identify microscopic structures is frequently enhanced through the use of histological stains, histology is an essential tool of biology and medicine. Trained physicians, frequently licensed pathologists, are the personnel who perform histopathological examination and their field of study is called histotechnology. In the 17th century, Italian Marcello Malpighi invented one of the first microscopes for studying tiny biological entities, Malpighi analysed several parts of the organs of bats, frogs and other animals under the microscope. Malpighi, while studying the structure of the lung, noticed its membranous alveoli and his discovery established how the oxygen we breathe enters the blood stream and serves the body. In the 19th century, histology was a discipline in its own right. The French anatomist Bichat introduced the concept of tissue in anatomy in 1801, the 1906 Nobel Prize in Physiology or Medicine was awarded to histologists Camillo Golgi and Santiago Ramon y Cajal. They had dueling interpretations of the structure of the brain based in differing interpretations of the same images. Cajal won the prize for his theory and Golgi for the staining technique he invented to make it possible. There are four types of animal tissues, muscle tissue, nervous tissue, connective tissue. All tissue types are subtypes of these four basic tissue types and their structure is very different from animal tissues. The most common fixative for light microscopy is 10% neutral buffered formalin, for electron microscopy, the most commonly used fixative is glutaraldehyde, usually as a 2. 5% solution in phosphate buffered saline. These fixatives preserve tissues or cells mainly by irreversibly cross-linking proteins and this can be detrimental to certain histological techniques. Further fixatives are often used for electron microscopy such as osmium tetroxide or uranyl acetate Formalin fixation leads to degradation of mRNA, miRNA and DNA in tissues, however, extraction, amplification and analysis of these nucleic acids from formalin-fixed, paraffin-embedded tissues is possible using appropriate protocols. Frozen section procedure is a way to fix and mount histology sections using a refrigeration device called a cryostat. It is often used after surgical removal of tumors to allow determination of margin
9.
Blue
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Blue is the colour between violet and green on the optical spectrum of visible light. Human eyes perceive blue when observing light with a wavelength between 450 and 495 nanometres, which is between 4500 and 4950 ångströms. Blues with a frequency and thus a shorter wavelength gradually look more violet, while those with a lower frequency. Pure blue, in the middle, has a wavelength of 470 nanometers, in painting and traditional colour theory, blue is one of the three primary colours of pigments, along with red and yellow, which can be mixed to form a wide gamut of colours. Red and blue mixed together form violet, blue and yellow together form green, Blue is also a primary colour in the RGB colour model, used to create all the colours on the screen of a television or computer monitor. The clear sky and the sea appear blue because of an optical effect known as Rayleigh scattering. When sunlight passes through the atmosphere, the wavelengths are scattered more widely by the oxygen and nitrogen molecules. An optical effect called Tyndall scattering, similar to Rayleigh scattering, explains blue eyes, distant objects appear more blue because of another optical effect called atmospheric perspective. Blue has been used for art and decoration since ancient times and it is the most important color in Judaism. In the Middle Ages, cobalt blue was used to colour the stained glass windows of cathedrals, beginning in the 9th century, Chinese artists used cobalt to make fine blue and white porcelain. Blue dyes for clothing were made from woad in Europe and indigo in Asia, in 1828 a synthetic ultramarine pigment was developed, and synthetic blue dyes and pigments gradually replaced mineral pigments and vegetable dyes. Pierre-Auguste Renoir, Vincent van Gogh and other late 19th century painters used ultramarine and cobalt blue not just to depict nature, in the late 18th century and 19th century, blue became a popular colour for military uniforms and police uniforms. In the 20th century, because blue was associated with harmony, it was chosen as the colour of the flags of the United Nations. Surveys in the US and Europe show that blue is the colour most commonly associated with harmony, faithfulness, confidence, distance, infinity, the imagination, cold, and sometimes with sadness. In US and European public opinion polls it is the most popular colour, Blue is the colour of light between violet and green on the visible spectrum. Blues also vary in shade or tint, darker shades of blue contain black or grey, darker shades of blue include ultramarine, cobalt blue, navy blue, and Prussian blue, while lighter tints include sky blue, azure, and Egyptian blue. Today most blue pigments and dyes are made by a chemical process, the modern English word blue comes from Middle English bleu or blewe, from the Old French bleu, a word of Germanic origin, related to the Old High German word blao. In heraldry, the azure is used for blue
10.
Violet (color)
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Violet is the color of amethyst, lavender and beautyberries. It takes its name from the violet flower, Violet is the color at the end of the visible spectrum of light between blue and the invisible ultraviolet. Violet color has a predominant light wavelength of roughly 380-450 nanometers, light with a shorter wavelength than violet but longer than X-rays and gamma rays is called ultraviolet. In the color wheel used by painters, it is located between blue and purple. This is not true violet, since it is composed of multiple longer wavelengths rather than a wavelength shorter than that of blue light. Violet and purple look very similar, but violet is a color, with its own set of wavelengths on the spectrum of visible light, while purple is a composite color, made by combining blue. In history, violet and purple have long associated with royalty and majesty. The emperors of Rome wore purple togas, as did the Byzantine emperors, during the Middle Ages violet was worn by bishops and university professors and was often used in art as the color of the robes of the Virgin Mary. According to surveys in Europe and the United States, violet is the people most often associate with extravagance and individualism, the unconventional, the artificial. In Chinese painting, the color represents the harmony of the universe because it is a combination of red. In Hinduism and Buddhism violet is associated with the Crown Chakra, from the Middle English and old French violette, and from the Latin viola, the names of the violet flower. The first recorded use of violet as a name in English was in 1370. Violet can also refer to the first violas which were painted a similar color. In the traditional color used by painters, violet and purple are both placed between red and blue. Purple occupies the space closer to red, between crimson and violet, Violet is closer to blue, and usually less intense and bright than purple. The range of purples is created by combining blue and red light of any intensities, Violet is one of the oldest colors used by man. It has also found in the cave of Altamira and Lascaux. It was sometimes used an alternative to black charcoal, sticks of manganese, used for drawing, have been found at sites occupied by Neanderthal man in France and Israel
11.
Red
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Red is the color at the longer-wavelengths end of the spectrum of visible light next to orange, at the opposite end from violet. Red color has a predominant light wavelength of roughly 620–740 nanometers, light with a longer wavelength than red but shorter than terahertz radiation and microwave is called infrared. Red is one of the secondary colors, resulting from the combination of yellow. Traditionally, it was viewed as a primary colour, along with yellow and blue, in the RYB color space and traditional color wheel formerly used by painters. Reds can vary in shade from light pink to very dark maroon or burgundy. Red is the color of cyan. In nature, the red color of blood comes from hemoglobin, the red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide. It also causes the red color of the planet Mars, the color of autumn leaves is caused by pigments called anthocyanins, which are produced towards the end of summer, when the green chlorophyll is no longer produced. One to two percent of the population has red hair, the color is produced by high levels of the reddish pigment pheomelanin. Since red is the color of blood, it has historically been associated with sacrifice, danger, modern surveys in the United States and Europe show red is also the color most commonly associated with heat, activity, passion, sexuality, anger, love and joy. In China, India and many other Asian countries it is the color of symbolizing happiness, since the 19th century, red has also been associated with socialism and communism. The word red is derived from the Old English rēad, the word can be further traced to the Proto-Germanic rauthaz and the Proto-Indo European root rewdʰ-. In Sanskrit, the word means red or blood. In the Akkadian language of Ancient Mesopotamia and in the modern Inuit language of Inuit, the words for colored in Latin and Spanish both also mean red. In Portuguese the word for red is vermelho, which comes from Latin vermiculus, in the Russian language, the word for red, Кра́сный, comes from the same old Slavic root as the words for beautiful—красивый and excellent—прекрасный. Thus Red Square in Moscow, named long before the Russian Revolution, in heraldry, the word gules is used for red. Red can vary in hue from orange-red to violet-red, and for each hue there is a variety of shades and tints. Red hematite powder was found scattered around the remains at a grave site in a Zhoukoudian cave complex near Beijing
12.
Eosinophilic
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Eosinophilic refers to the staining of certain tissues, cells, or organelles after they have been washed with eosin, a dye. Eosin is a dye, thus, the structure being stained is basic. Eosinophilic describes the appearance of cells and structures seen in sections that take up the staining dye eosin. This is a dye that stains the cytoplasm of cells. Such eosinophilic structures are, in general, composed of protein, the stain eosin is usually combined with a stain called hematoxylin to produce a hematoxylin- and eosin-stained section. This is the most widely used stain in medical diagnosis, for example, when a pathologist examines a biopsy of a suspected cancer. Some structures seen inside cells are described as being eosinophilic, for example, Lewy bodies, some cells are also described as eosinophilic, such as Leukocytes
13.
Chromatin
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Chromatin is a complex of macromolecules found in cells, consisting of DNA, protein, and RNA. The primary protein components of chromatin are histones that compact the DNA, Chromatin is only found in eukaryotic cells. Prokaryotic cells have a different organization of their DNA, the structure of chromatin depends on several factors. The overall structure depends on the stage of the cell cycle, during interphase, the chromatin is structurally loose to allow access to RNA and DNA polymerases that transcribe and replicate the DNA. The local structure of chromatin during interphase depends on the present on the DNA. As the cell prepares to divide, i. e. enters mitosis or meiosis, during this stage of the cell cycle this makes the individual chromosomes in many cells visible by optical microscope. In general terms, there are three levels of organization, DNA wraps around histone proteins forming nucleosomes, the beads on a string structure. Multiple histones wrap into a 30 nm fibre consisting of nucleosome arrays in their most compact form, higher-level DNA packaging of the 30 nm fibre into the metaphase chromosome. There are, however, many cells that do not follow this organisation, Chromatin undergoes various structural changes during a cell cycle. Histone proteins are the basic packer and arranger of chromatin and can be modified by various modifications to alter chromatin packing. Most of the modifications occur on the histone tail, the consequences in terms of chromatin accessibility and compaction depend both on the amino-acid that is modified and the type of modification. For example, Histone acetylation results in loosening and increased accessibility of chromatin for replication and transcription, lysine tri-methylation can either be correlated with transcriptional activity or transcriptional repression and chromatin compaction. Several studies suggested that different modifications could occur simultaneously, for example, it was proposed that a bivalent structure was involved in mammalian early development. Polycomb-group proteins play a role in regulating genes through modulation of chromatin structure, for additional information, see Histone modifications in chromatin regulation and RNA polymerase control by chromatin structure. In nature, DNA can form three structures, A-, B-, and Z-DNA, A- and B-DNA are very similar, forming right-handed helices, whereas Z-DNA is a left-handed helix with a zig-zag phosphate backbone. Z-DNA is thought to play a role in chromatin structure. At the junction of B- and Z-DNA, one pair of bases is flipped out from normal bonding and these play a dual role of a site of recognition by many proteins and as a sink for torsional stress from RNA polymerase or nucleosome binding. In addition to the histones, there is the linker histone, H1
14.
Protein
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Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, a linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide, short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides, or sometimes oligopeptides. The individual amino acid residues are bonded together by peptide bonds, the sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the code specifies 20 standard amino acids, however. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors, proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes. Once formed, proteins only exist for a period of time and are then degraded and recycled by the cells machinery through the process of protein turnover. A proteins lifespan is measured in terms of its half-life and covers a wide range and they can exist for minutes or years with an average lifespan of 1–2 days in mammalian cells. Abnormal and or misfolded proteins are degraded more rapidly due to being targeted for destruction or due to being unstable. Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms, many proteins are enzymes that catalyse biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle. In animals, proteins are needed in the diet to provide the essential amino acids that cannot be synthesized, digestion breaks the proteins down for use in the metabolism. Methods commonly used to study structure and function include immunohistochemistry, site-directed mutagenesis, X-ray crystallography, nuclear magnetic resonance. Most proteins consist of linear polymers built from series of up to 20 different L-α-amino acids, all proteinogenic amino acids possess common structural features, including an α-carbon to which an amino group, a carboxyl group, and a variable side chain are bonded. Only proline differs from this structure as it contains an unusual ring to the N-end amine group. The amino acids in a chain are linked by peptide bonds. Once linked in the chain, an individual amino acid is called a residue, and the linked series of carbon, nitrogen. The peptide bond has two forms that contribute some double-bond character and inhibit rotation around its axis, so that the alpha carbons are roughly coplanar
15.
Lewy body
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Lewy bodies are abnormal aggregates of protein that develop inside nerve cells in Parkinsons disease, Lewy body dementia, and some other disorders. They are identified under the microscope when histology is performed on the brain, Lewy bodies appear as spherical masses that displace other cell components. Lewy bodies may be found in the brainstem or within the cortex, cortical Lewy bodies are also composed of alpha-synuclein fibrils, but are less defined and lack halos. They are also seen in cases of multiple system atrophy, particularly the parkinsonian variant, in 1910 Fritz Heinrich Lewy studied in Berlin to get his doctorate. His finding became known as Lewy bodies, as published in the Handbook of Neurology in 1912, according to the Journal of the History of the Neurosciences, Dr. Lewy became interested in studying more about the brain, because of the discovery that Alois Alzheimer made in 1906. A Lewy body is composed of the protein associated with other proteins, such as ubiquitin, neurofilament protein. Tau proteins may also be present, and Lewy bodies may occasionally be surrounded by neurofibrillary tangles, Lewy bodies and NFTs can occasionally exist in the same neuron, particularly in the amygdala. Lewy bodies are believed to represent a response in the cell. Lewy neurites are abnormal neurites in diseased neurons, containing granular material and abnormal α-synuclein filaments similar to found in Lewy bodies. Like Lewy bodies, Lewy neurites are a feature of such as dementia with Lewy bodies, Parkinsons disease. They are also found in the CA2-3 region of the hippocampus in Alzheimers disease, ella Harris tells Chicago Mayor Tom Kane he has Lewy bodies, and his progressing symptoms are shown in each episode
16.
Mallory body
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In histopathology, a Mallory body, Mallory-Denk body, and Mallorys hyaline, is an inclusion found in the cytoplasm of liver cells. Mallory bodies are damaged intermediate filaments within the hepatocytes, Mallory bodies are classically found in the livers of people suffering from alcoholic liver disease and were once thought to be specific for that. They are most common in hepatitis and alcoholic cirrhosis. They are a feature of Wilsons disease, primary biliary cirrhosis, non-alcoholic cirrhosis, hepatocellular carcinoma and morbid obesity. However, it has also reported in certain other unrelated conditions. Mallory bodies are highly eosinophilic and thus appear pink on H&E stain, the bodies themselves are made up of intermediate cytokeratin 8/18 filament proteins that have been ubiquinated, or bound by other proteins such as heat shock proteins, or p62. It is named for the American pathologist Frank Burr Mallory, who first described the structures in 1911 and they were renamed as Mallory-Denk bodies in 2007 to honor the contribution of Austrian pathologist Helmut Denk for the molecular analysis of the pathogenesis of MDBs. Ballooning degeneration - another histopathologic finding of steatohepatitis
17.
Cytoplasm
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In cell biology, the cytoplasm is the material within a living cell, excluding the cell nucleus. It comprises cytosol and the organelles – the cells internal sub-structures, all of the contents of the cells of prokaryotic organisms are contained within the cytoplasm. Within the cells of organisms the contents of the cell nucleus are separated from the cytoplasm. The cytoplasm is about 80% water and usually colorless, the submicroscopic ground cell substance or cytoplasmatic matrix which remains after exclusion the cell organelles and particles is groundplasm. It is within the cytoplasm that most cellular activities occur, such as many metabolic pathways including glycolysis, the concentrated inner area is called the endoplasm and the outer layer is called the cell cortex or the ectoplasm. Movement of calcium ions in and out of the cytoplasm is an activity for metabolic processes. In plants, movement of the cytoplasm around vacuoles is known as cytoplasmic streaming, the term was introduced by Rudolf von Kölliker in 1863, originally as a synonym for protoplasm, but later it has come to mean the cell substance and organelles outside the nucleus. There has been disagreement on the definition of cytoplasm, as some authors prefer to exclude from it some organelles. The physical properties of the cytoplasm have been contested in recent years and it remains uncertain how the varied components of the cytoplasm interact to allow movement of particles and organelles while maintaining the cell’s structure. The flow of cytoplasmic components plays an important role in cellular functions which are dependent on the permeability of the cytoplasm. An example of function is cell signalling, a process which is dependent on the manner in which signaling molecules are allowed to diffuse across the cell. While small signaling molecules like calcium ions are able to diffuse with ease, larger molecules, the irregular dynamics of such particles have given rise to various theories on the nature of the cytoplasm. There has long been evidence that the cytoplasm behaves like a sol-gel and it is thought that the component molecules and structures of the cytoplasm behave at times like a disordered colloidal solution and at other times like an integrated network, forming a solid mass. Recently it has proposed that the cytoplasm behaves like a glass-forming liquid approaching the glass transition. A cells ability to vitrify in the absence of activity, as in dormant periods. There has been examining the motion of cytoplasmic particles independent of the nature of the cytoplasm. In such an approach, the aggregate random forces within the cell caused by motor proteins explain the non-Brownian motion of cytoplasmic constituents. The three major elements of the cytoplasm are the cytosol, organelles and inclusions, the cytosol is the portion of the cytoplasm not contained within membrane-bound organelles
18.
Red blood cell
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RBCs take up oxygen in the lungs, or gills of fish, and release it into tissues while squeezing through the bodys capillaries. The cytoplasm of erythrocytes is rich in hemoglobin, a biomolecule that can bind oxygen and is responsible for the red color of the cells. In humans, mature red cells are flexible and oval biconcave disks. They lack a nucleus and most organelles, in order to accommodate maximum space for hemoglobin, they can be viewed as sacks of hemoglobin. Approximately 2.4 million new erythrocytes are produced per second in human adults, the cells develop in the bone marrow and circulate for about 100–120 days in the body before their components are recycled by macrophages. Each circulation takes about 60 seconds, approximately a quarter of the cells in the human body are red blood cells. Nearly half of the volume is red blood cells. Red blood cells are known as RBCs, red cells, red blood corpuscles, haematids. Packed red blood cells are red blood cells that have donated, processed. Almost all vertebrates, including all mammals and humans, have red blood cells, red blood cells are cells present in blood in order to transport oxygen. The only known vertebrates without red blood cells are the crocodile icefish, they live in very cold water. While they no longer use hemoglobin, remnants of hemoglobin genes can be found in their genome, oxygen can easily diffuse through the red blood cells cell membrane. Myoglobin, a related to hemoglobin, acts to store oxygen in muscle cells. The color of red cells is due to the heme group of hemoglobin. However, blood can appear bluish when seen through the vessel wall, pulse oximetry takes advantage of the hemoglobin color change to directly measure the arterial blood oxygen saturation using colorimetric techniques. Hemoglobin also has a high affinity for carbon monoxide, forming carboxyhemoglobin which is a very bright red in color. Flushed, confused patients with a reading of 100% on pulse oximetry are sometimes found to be suffering from carbon monoxide poisoning. The red blood cells of mammals are typically shaped as disks, flattened and depressed in the center, with a dumbbell-shaped cross section
19.
Melanin
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Melanin /ˈmɛlənɪn/ is a broad term for a group of natural pigments found in most organisms. Melanin is produced by the oxidation of the amino acid tyrosine, the pigment is produced in a specialized group of cells known as melanocytes. There are three types of melanin, eumelanin, pheomelanin, and neuromelanin. The most common is eumelanin, of which there are two types—brown eumelanin and black eumelanin, pheomelanin is a cysteine-containing red polymer of benzothiazine units largely responsible for red hair, among other pigmentation. Neuromelanin is found in the brain, though its function remains obscure, in the skin, melanogenesis occurs after exposure to UV radiation, causing the skin to visibly tan. Melanin is an effective absorber of light, the pigment is able to dissipate over 99. 9% of absorbed UV radiation, because of this property, melanin is thought to protect skin cells from UVB radiation damage, reducing the risk of cancer. e. Nonetheless, the relationship between skin pigmentation and photoprotection is still being clarified, in humans, melanin is the primary determinant of skin color. It is also found in hair, the pigmented tissue underlying the iris of the eye, in the brain, tissues with melanin include the medulla and pigment-bearing neurons within areas of the brainstem, such as the locus coeruleus and the substantia nigra. It also occurs in the zona reticularis of the adrenal gland, the melanin in the skin is produced by melanocytes, which are found in the basal layer of the epidermis. Although, in general, human beings possess a concentration of melanocytes in their skin. Some humans have very little or no melanin synthesis in their bodies, because melanin is an aggregate of smaller component molecules, there are many different types of melanin with differing proportions and bonding patterns of these component molecules. Both pheomelanin and eumelanin are found in skin and hair. Eumelanin polymers have long thought to comprise numerous cross-linked 5, 6-dihydroxyindole and 5. There are two types of eumelanin and black eumelanin—which chemically differ from each other in their pattern of polymeric bonds. A small amount of black eumelanin in the absence of other pigments causes grey hair, a small amount of brown eumelanin in the absence of other pigments causes blond color hair. As the body ages, it continues to produce black melanin but stops producing the brown version, pheomelanins impart a pink to red hue, depending upon the concentration. Pheomelanins are particularly concentrated in the lips, nipples, glans of the penis, when a small amount of brown eumelanin in hair, which would otherwise cause blond hair, is mixed with red pheomelanin, the result is red hair. Pheomelanin is also present in the skin, and redheads consequently often have a pinkish hue to their skin as well
20.
Basal lamina
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The basal lamina is a layer of extracellular matrix secreted by the epithelial cells, on which the epithelium sits. It is often referred to as the basement membrane, though it does constitute a portion of the basement membrane. The basal lamina is only with the electron microscope, where it appears as an electron-dense layer that is 20-100 nm thick. Although found beneath all basal laminae, they are numerous in stratified squamous cells of the skin. These layers should not be confused with the lamina propria, which is found outside the basal lamina, the basement membrane is visible under light microscopy. Electron microscopy shows that the basement membrane consists of three layers, the lamina lucida, lamina densa, and lamina fibroreticularis, the lamina densa was formerly known as the basal lamina. This has led to considerable confusion and, if used. Some theorize that the lamina lucida is an artifact created when preparing the tissue, the term basal lamina is usually used with electron microscopy, while the term basement membrane is usually used with light microscopy. Examples of basement membranes include, Basilar membrane Bruchs membrane Descemets membrane Glomerular basement membrane The basal lamina is made and it acts as a point of attachment for cells. However, it can also have other function such as a permeability barrier in the glomerulus, alport’s syndrome is a genetic disorder resulting from mutations in the COL4A3/4/5 genes. These genes are important in collagen IV synthesis and basement membrane formation, alveolar-capillary barrier Basolateral membrane Collagen Glomerular basement membrane Lamina propria Reticular lamina MBInfo - The Extracellular Matrix and Basal Lamina
21.
Silver stain
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Silver staining is the use of silver to selectively alter the appearance of a target in microscopy of histological sections, in temperature gradient gel electrophoresis, and in polyacrylamide gels. Camillo Golgi perfected silver staining for the study of the nervous system, although the exact chemical mechanism by which this occurs is unknown, Golgis method stains a limited number of cells at random in their entirety. Silver staining was introduced by Kerenyi and Gallyas as a procedure to detect trace amounts of proteins in gels. The technique has been extended to the study of biological macromolecules that have been separated in a variety of supports. Classical Coomassie Brilliant Blue staining can usually detect a 50 ng protein band and these reduce silver solution to metallic silver after formalin fixation. These reduce silver solution to metallic silver after being exposed to the stain that contains a reductant, silver nitrate forms insoluble silver phosphate with phosphate ions, this method is known as the Von Kossa Stain. When subjected to an agent, usually hydroquinone, it forms black elementary silver. This is used for study of formation of calcium phosphate particles during bone growth, pseudomonas, Legionella, Leptospira, H. pylori, and fungi such as Pneumocystis and Candida are organisms that are stained with silver. Silver staining is used in karyotyping, silver nitrate stains the nucleolar organization region -associated protein, producing a dark region wherein the silver is deposited and denoting the activity of rRNA genes within the NOR. Human chromosomes 13,14,15,21, and 22 have NORs, silver staining is used to stain gels. Silver staining is also a technique in traditional stained glass to produce the yellow, brown and it is a technique that is often used for realistic hair colors. It was discovered in the 14th Century but was not originally used very frequently, there are several silver stains incorporating methenamine, including, Grocotts methenamine silver stain, used widely as a screen for fungal organisms. Jones stain, a methenamine silver-Periodic acid-Schiff that stains for basement membrane, medEd at Loyola Histo/practical/stains/hp2-55. html Hempelmann E. SDS-Protein PAGE and protein detection by silverstaining and immunoblotting of Plasmodium falciparum proteins. In, Moll K, Ljungström J, Perlmann H, Scherf A, Wahlgren M Methods in Malaria Research, 5th edition,2008, 263-266
22.
Reticular fiber
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Reticular fibers, reticular fibres or reticulin is a type of fiber in connective tissue composed of type III collagen secreted by reticular cells. Reticular fibers crosslink to form a fine meshwork and this network acts as a supporting mesh in soft tissues such as liver, bone marrow, and the tissues and organs of the lymphatic system. The term reticulin was coined in 1892 by M. Siegfried, today, the term reticulin or reticular fiber is restricted to referring to fibers composed of type III collagen. The history of the silver stain is reviewed by Puchtler et al. The abstract of this says, Maresch introduced Bielschowskys silver impregnation technic for neurofibrils as a stain for reticulum fibers. This lack of specificity has been confirmed repeatedly, yet, since the 1920s the definition of reticulin and studies of its distribution were based solely on silver impregnation technics. The chemical mechanism and specificity of this group of stains is obscure, application of Gömöris and Wilders methods to human tissues showed variations of staining patterns with the fixatives and technics employed. Besides reticulum fibers, various other structures, e. g. I bands of striated muscle, fibers in nervous tissues, and model substances, e. g. polysaccharides, egg white, deposition of silver compounds on reticulum fibers was limited to an easily removable substance, the remaining collagen component did not bind silver. Reticular fiber is composed of one or more types of very thin and these strands build a highly ordered cellular network and provide a supporting network. Many of these types of collagen have been combined with carbohydrate, thus, they react with silver stains and with periodic acid-Schiff reagent but are not demonstrated with ordinary histological stains such as those using hematoxylin. In a 1993 paper, the fibers of the capillary sheath. This paper attempted to reveal their components and the presence of acid in the amorphous ground substance. Collagen fibrils, elastic fibers, microfibrils, nerve fibers, on the other hand, only microfibrils were recognized in the reticular fibers of the capillary sheath. The binding of LFA lectin to the cord was stronger than the capillary sheath. These findings suggested that the fibers of the splenic cord include multiple functional elements. On the other hand, the fiber of the capillary sheath resembled the basement membrane of the capillary in its components. Because of their affinity for silver salts, these fibers are called argyrophilic, reticulin at the US National Library of Medicine Medical Subject Headings MedEd at Loyola Histo/practical/stains/hp2-55. html
23.
Adipocyte
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Adipocytes, also known as lipocytes and fat cells, are the cells that primarily compose adipose tissue, specialized in storing energy as fat. There are two types of tissue, white adipose tissue and brown adipose tissue, which are also known as white fat and brown fat, respectively. Most recently, the presence of beige adipocytes with an expression pattern distinct from either white or brown adipocytes has been described. White fat cells or monovacuolar cells contain a lipid droplet surrounded by a layer of cytoplasm. The nucleus is flattened and located on the periphery, a typical fat cell is 0.1 mm in diameter with some being twice that size and others half that size. The fat stored is in a state, and is composed primarily of triglycerides. White fat cells secrete many proteins acting as such as resistin, adiponectin, leptin and apelin. An average human adult has 30 billion fat cells with a weight of 30 lbs or 13.5 kg, if excess weight is gained as an adult, fat cells increase in size about fourfold before dividing and increasing the absolute number of fat cells present. Brown fat cells or plurivacuolar cells are polygonal in shape, unlike white fat cells, these cells have considerable cytoplasm, with lipid droplets scattered throughout. The nucleus is round, and, although eccentrically located, it is not in the periphery of the cell, the brown color comes from the large quantity of mitochondria. Brown fat, also known as fat, is used to generate heat. Pre-adipocytes are undifferentiated fibroblasts that can be stimulated to form adipocytes, recent studies shed light into potential molecular mechanisms in the fate determination of pre-adipocytes although the exact lineage of adipocyte is still unclear. The variation of body fat distribution resulting from normal growth is influenced by nutritional and hormonal status in dependence on intrinsic differences in cells found in each adipose depot, mesenchymal stem cells can differentiate into adipocytes, connective tissue, muscle or bone. The term lipoblast is used to describe the precursor of the adult cell, the term lipoblastoma is used to describe a tumor of this cell type. Even after marked weight loss, the body never loses adipocytes. As a rule, to changes in weight. However, if the adipocytes in the body reach their capacity of fat. Adult rats of various strains became obese when they were fed a highly palatable diet for several months, analysis of their adipose tissue morphology revealed increases in both adipocyte size and number in most depots. Reintroduction of an ordinary chow diet to such animals precipitated a period of loss during which only mean adipocyte size returned to normal
24.
Myelin
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Myelin is a fatty white substance that surrounds the axon of some nerve cells, forming an electrically insulating layer. It is essential for the functioning of the nervous system. It is an outgrowth of a type of glial cell, the production of the myelin sheath is called myelination or myelinogenesis. In humans, myelination begins early in the 3rd trimester, although little myelin exists in the brain at the time of birth, during infancy, myelination occurs quickly, leading to a childs fast development, including crawling and walking in the first year. Myelination continues through the adolescent stage of life, schwann cells supply the myelin for the peripheral nervous system, whereas oligodendrocytes, specifically of the interfascicular type, myelinate the axons of the central nervous system. Myelin was discovered in 1854 by Rudolf Virchow, Myelin is made by different cell types, and varies in chemical composition and configuration, but performs the same insulating function. Myelinated axons are white in appearance, hence the matter of the brain. Myelin helps to insulate the axons from electrically charged atoms and molecules and these charged particles are found in the fluid surrounding the entire nervous system. Under a microscope, myelin looks like strings of sausages, cholesterol is an essential constituent of myelin. Myelin is about 40% water, the dry mass is about 70–85% lipids, some of the proteins are myelin basic protein, myelin oligodendrocyte glycoprotein, and proteolipid protein. The primary lipid of myelin is a glycolipid called galactocerebroside, the intertwining hydrocarbon chains of sphingomyelin serve to strengthen the myelin sheath. In brain, the myelin sheath covers the fibers of corpus callosum which constitute the part of cerebral hemisphere. The main purpose of a layer is to increase the speed at which impulses propagate along the myelinated fiber. Along unmyelinated fibers, impulses move continuously as waves, but, in myelinated fibers, Myelin decreases capacitance and increases electrical resistance across the cell membrane. Thus, myelination helps prevent the current from leaving the axon. It has been suggested that myelin permits larger body size by maintaining agile communication between distant body parts, myelinated fibers lack voltage-gated ion channels along the myelinated internodes, exposing them only at the nodes of Ranvier. Here, they are far more abundantly. Myelinated fibers succeed in reducing sodium leakage into the extracellular fluid and this increases sodium’s ability to travel along the axon more freely
25.
Axon
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An axon, is a long, slender projection of a nerve cell, or neuron, that typically conducts electrical impulses away from the neurons cell body. Axons are also known as nerve fibers, the function of the axon is to transmit information to different neurons, muscles and glands. Axon dysfunction has caused many inherited and acquired neurological disorders which can affect both the peripheral and central neurons, nerve fibers are classed into three types – A delta fibers, B fibers, and C fibres. A and B are myelinated and C are unmyelinated, an axon is one of two types of protoplasmic protrusions that extrude from the cell body of a neuron, the other type being dendrites. Axons are distinguished from dendrites by several features, including shape, length, all of these rules have exceptions, however. Axons are covered by a known as axolemma, the cytoplasm of axon is called axoplasm. Some types of neurons have no axon and transmit signals from their dendrites, no neuron ever has more than one axon, however in invertebrates such as insects or leeches the axon sometimes consists of several regions that function more or less independently of each other. Most axons branch, in cases very profusely. Axons make contact with other cells—usually other neurons but sometimes muscle or gland cells—at junctions called synapses, at a synapse, the membrane of the axon closely adjoins the membrane of the target cell, and special molecular structures serve to transmit electrical or electrochemical signals across the gap. Some synaptic junctions appear partway along an axon as it extends—these are called en passant synapses, other synapses appear as terminals at the ends of axonal branches. A single axon, with all its branches together, can innervate multiple parts of the brain. Axons are the transmission lines of the nervous system. Some axons can extend up to one meter or more while others extend as little as one millimeter, the longest axons in the human body are those of the sciatic nerve, which run from the base of the spinal cord to the big toe of each foot. The diameter of axons is also variable, most individual axons are microscopic in diameter. The largest mammalian axons can reach a diameter of up to 20 µm, the squid giant axon, which is specialized to conduct signals very rapidly, is close to 1 millimetre in diameter, the size of a small pencil lead. Axonal arborization also differs from one nerve fiber to the next, axons in the central nervous system typically show complex trees with many branch points. In comparison, the granule cell axon is characterized by a single T-shaped branch node from which two parallel fibers extend. Elaborate arborization allows for the transmission of messages to a large number of target neurons within a single region of the brain
26.
Golgi apparatus
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The Golgi apparatus, also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. It was identified in 1897 by the Italian scientist Camillo Golgi, part of the cellular endomembrane system, the Golgi apparatus packages proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination. The Golgi apparatus resides at the intersection of the secretory, lysosomal, owing to its large size and distinctive structure, the Golgi apparatus was one of the first organelles to be discovered and observed in detail. It was discovered in 1898 by Italian physician Camillo Golgi during an investigation of the nervous system, after first observing it under his microscope, he termed the structure the internal reticular apparatus. Some doubted the discovery at first, arguing that the appearance of the structure was merely an illusion created by the observation technique used by Golgi. With the development of modern microscopes in the 20th century, the discovery was confirmed, early references to the Golgi referred to it by various names including the Golgi–Holmgren apparatus, Golgi–Holmgren ducts, and Golgi–Kopsch apparatus. The term Golgi apparatus was used in 1910 and first appeared in the literature in 1913. Among eukaryotes, the localization of the Golgi apparatus differs. In mammals, a single Golgi apparatus complex is located near the cell nucleus. Tubular connections are responsible for linking the stacks together, localization and tubular connections of the Golgi apparatus are dependent on microtubules. If microtubules are experimentally depolymerized, then the Golgi apparatus loses connections, in yeast, multiple Golgi apparatuses are scattered throughout the cytoplasm. In plants, Golgi stacks are not concentrated at the centrosomal region, organization of the plant Golgi depends on actin cables and not microtubules. The common feature among Golgi is that they are adjacent to endoplasmic reticulum exit sites, in most eukaryotes, the Golgi apparatus is made up of a series of compartments consisting of two main networks, the cis Golgi network and the trans Golgi network. The CGN is a collection of fused, flattened membrane-enclosed disks known as cisternae, a mammalian cell typically contains 40 to 100 stacks. Between four and eight cisternae are usually present in a stack, however and this collection of cisternae is broken down into cis, medial, and trans compartments. The TGN is the final structure, from which proteins are packaged into vesicles destined to lysosomes, secretory vesicles. The TGN is usually positioned adjacent to the stacks of the Golgi apparatus, the TGN may act as an early endosome in yeast and plants. There are structural and organizational differences in the Golgi apparatus among eukaryotes, in some yeasts, Golgi stacking is not observed
27.
Papanicolaou stain
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Papanicolaou stain is a multichromatic staining cytological technique developed by George Papanikolaou, the father of cytopathology. Pap staining is a reliable technique. As such, it is used for cancer screening in gynecology. The entire procedure is known as Pap smear, the classic form of Pap stain involves five dyes in three solutions, A nuclear stain, haematoxylin, is used to stain cell nuclei. The unmordanted haematein may be responsible for the yellow color imparted to glycogen and its original role was to stain the small cells of keratinizing squamous cell carcinoma present in sputum. Second EA counterstain, comprising three dyes, the number denotes the proportion of the dyes, e. g. EA-36, EA-50, eosin Y stains the superficial epithelial squamous cells, nucleoli, cilia, and red blood cells. Light Green SF yellowish stains the cytoplasm of cells, including non-keratinized squamous cells. Bismarck brown Y stains nothing and in contemporary formulations it is often omitted, when performed properly, the stained specimen should display hues from the entire spectrum, red, orange, yellow, green, blue, and violet. The chromatin patterns are visible, the cells from borderline lesions are easier to interpret. The staining results in very transparent cells, so even thicker specimens with overlapping cells can be interpreted, on a well prepared specimen, the cell nuclei are crisp blue to black. Cells with high content of keratin are yellow, glycogen stains yellow as well, superficial cells are orange to pink, and intermediate and parabasal cells are turquoise green to blue. Metaplastic cells often stain both green and pink at once, Pap stain is not fully standardized, it comes in several versions, subtly differing in the exact dyes used, their ratios, and timing of the process. The descriptions of the compositions of the staining solutions vary by source, mixtures of the same name from different vendors therefore can differ in composition, occasionally producing different or poor results. Ultrafast Papanicolaou stain is an alternative for the fine needle aspiration samples, h&E stain, other popular staining technique Staining Wright stain, used for cerebrospinal fluid and suspected lymphomas
28.
Cytopathology
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Cytopathology is a branch of pathology that studies and diagnoses diseases on the cellular level. The discipline was founded by George Nicolas Papanicolaou in 1928, a common application of cytopathology is the Pap smear, used as a screening tool, to detect precancerous cervical lesions and prevent cervical cancer. Cytopathology is also used to investigate thyroid lesions, diseases involving sterile body cavities. It is usually used to aid in the diagnosis of cancer, cytopathology is generally used on samples of free cells or tissue fragments, in contrast to histopathology, which studies whole tissues. Cytopathologic tests are sometimes called smear tests because the samples may be smeared across a glass slide for subsequent staining. However, cytology samples may be prepared in ways, including cytocentrifugation. Different types of tests may also be used for cancer diagnosis. In this sense, it is termed a cytologic smear, cytopathology is frequently, less precisely, called cytology, which means the study of cells. An example of spontaneous exfoliation is when cells of the cavity or peritoneal cavity are shed into the pleural or peritoneal fluid. This fluid can be collected via various methods for examination, liquid-based cytology collects the samples in the same way but places them in liquid that is then treated to allow for improved results. In interventional cytology the pathologist intervenes into the body for sample collection, nowadays FNAC has become synonymous to interventional cytology. Fine-Needle Aspiration Cytology or Needle aspiration biopsy, a needle attached to a syringe is used to collect cells from lesions or masses in various body organs by microcoring, often with the application of negative pressure to increase yield. FNAC is widely used in countries, but success rate is dependent on the skill of the practitioner. If performed by a pathologist alone, or as team with pathologist-cytotechnologist and this may be due to the pathologists ability to immediately evaluate specimens under a microscope and immediately repeat the procedure if sampling was inadequate. Fine needles are 23 to 27 gauge, because needles as small as 27 gauge can almost always yield diagnostic material, FNAC is often the least injurious way to obtain diagnostic tissue from a lesion. Sometime a syringe holder may be used to using one hand to perform the biopsy while the other hand is immobilizing the mass. Imaging equipment such as a CT scanner or ultrasound may be used to assist in locating the region to be biopsied, sediment cytology – Here, the sample is collected from the fixative that was used for processing the biopsy or autopsy specimen. The fixative is mixed properly and taken into a tube and is centrifuged
29.
Acid-fastness
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Acid-fastness is a physical property of certain bacteria, specifically their resistance to decolorization by acids during laboratory staining procedures. Once stained as part of a sample, these organisms can resist the acid and/or ethanol-based de-colorization procedures common in many staining protocols, hence the name acid-fast. The high mycolic acid content of certain Protozoa cell walls, another method is the Kinyoun method, in which the bacteria are stained bright red and stand out clearly against a green background. Acid-fast Mycobateria can also be visualized by microscopy using specific fluorescent dyes. Some bacteria may also be partially acid-fast, the following are notable examples of structures which are acid fast or modified acid fast, All Mycobacteria - M. tuberculosis, M. leprae, M. g. Cytoplasmic inclusion bodies seen in Neurons in layer 5 of cerebral cortex neuronal ceroid lipofuscinosis, nuclear inclusion bodies seen in Lead poisoning Bismuth poisoning. Oocysts of some coccidian parasites in faecal matter, such as, Cryptosporidium parvum, fungal yeast forms are inconsistently stained with Acid-fast stain which is considered a narrow spectrum stain for fungi. Alternate Ellis & Zabrowarny method for staining AFB
30.
Iron
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Iron is a chemical element with symbol Fe and atomic number 26. It is a metal in the first transition series and it is by mass the most common element on Earth, forming much of Earths outer and inner core. It is the fourth most common element in the Earths crust, like the other group 8 elements, ruthenium and osmium, iron exists in a wide range of oxidation states, −2 to +6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen, fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike the metals that form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, Iron metal has been used since ancient times, although copper alloys, which have lower melting temperatures, were used even earlier in human history. Pure iron is soft, but is unobtainable by smelting because it is significantly hardened and strengthened by impurities, in particular carbon. A certain proportion of carbon steel, which may be up to 1000 times harder than pure iron. Crude iron metal is produced in blast furnaces, where ore is reduced by coke to pig iron, further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and iron alloys formed with metals are by far the most common industrial metals because they have a great range of desirable properties. Iron chemical compounds have many uses, Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. Iron forms binary compounds with the halogens and the chalcogens, among its organometallic compounds is ferrocene, the first sandwich compound discovered. Iron plays an important role in biology, forming complexes with oxygen in hemoglobin and myoglobin. Iron is also the metal at the site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants. A human male of average height has about 4 grams of iron in his body and this iron is distributed throughout the body in hemoglobin, tissues, muscles, bone marrow, blood proteins, enzymes, ferritin, hemosiderin, and transport in plasma. The mechanical properties of iron and its alloys can be evaluated using a variety of tests, including the Brinell test, Rockwell test, the data on iron is so consistent that it is often used to calibrate measurements or to compare tests. An increase in the content will cause a significant increase in the hardness. Maximum hardness of 65 Rc is achieved with a 0. 6% carbon content, because of the softness of iron, it is much easier to work with than its heavier congeners ruthenium and osmium. Because of its significance for planetary cores, the properties of iron at high pressures and temperatures have also been studied extensively
31.
Hemosiderin
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Hemosiderin or haemosiderin is an iron-storage complex. It is only found within cells and appears to be a complex of ferritin, denatured ferritin, the iron within deposits of hemosiderin is very poorly available to supply iron when needed. Hemosiderin can be identified histologically with Perls Prussian-blue stain, in normal animals, hemosiderin deposits are small and commonly inapparent without special stains. Excessive accumulation of hemosiderin is usually detected within cells of the mononuclear phagocyte system or occasionally within epithelial cells of liver, several disease processes result in deposition of larger amounts of hemosiderin in tissues, although these deposits often cause no symptoms, they can lead to organ damage. Hemosiderin can accumulate in different organs in various diseases, iron is required by many of the chemical reactions in the body but is toxic when not properly contained. Thus, many methods of iron storage have developed, when blood leaves a ruptured blood vessel, the red blood cell dies, and the hemoglobin of the cell is released into the extracellular space. Phagocytic cells called macrophages engulf the hemoglobin to degrade it, producing hemosiderin and biliverdin, excessive systemic accumulations of hemosiderin may occur in macrophages in the liver, lungs, spleen, kidneys, lymph nodes, and bone marrow. These accumulations may be caused by red blood cell destruction, excessive iron uptake/ hyperferraemia. Hemosiderin may deposit in diseases associated with iron overload and these diseases are typically diseases in which chronic blood loss requires frequent blood transfusions, such as sickle cell anemia and thalassemia
32.
Prussian blue
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Prussian blue is a dark blue pigment with the idealized chemical formula Fe 718. To better understand the situation in this complex compound the formula can also be written as Fe 43 · xH 2O. Another name for the color is Berlin blue or, in painting, Turnbulls blue is the same substance, but is made from different reagents, and its slightly different color stems from different impurities. Prussian blue was the first modern synthetic pigment and it is employed as a very fine colloidal dispersion, as the compound itself is not soluble in water. It is famously complex, owing to the presence of variable amounts of other ions, the pigment is used in paints, and it is the traditional blue in blueprints. In medicine, Prussian blue is used as an antidote for certain kinds of metal poisoning, e. g. by thallium. In particular it was used to absorb 137Cs+ from those poisoned in the Goiânia accident, the therapy exploits Prussian blues ion exchange properties and high affinity for certain soft metal cations. It is on the World Health Organizations List of Essential Medicines, Prussian blue lent its name to prussic acid, which was derived from it. In Germany, hydrogen cyanide is called Blausäure, and Joseph Louis Gay-Lussac gave cyanide its name, from the Greek word κυανός, because it is easily made, cheap, nontoxic, and intensely colored, Prussian blue has attracted many applications. It was adopted as a pigment very soon after its invention and was almost immediately used in oil, watercolor. The dominant uses are for pigments, about 12,000 tonnes of Prussian blue are produced annually for use in black, a variety of other pigments also contain the material. Engineers blue and the pigment formed on cyanotypes—giving them their common name blueprints, certain crayons were once colored with Prussian blue. It is also a popular pigment in paints, similarly, Prussian blue is the basis for laundry bluing. Prussian blues ability to incorporate monocations makes it useful as a agent for certain heavy metal poisons. Pharmaceutical-grade Prussian blue in particular is used for people who have ingested thallium or radioactive caesium, according to the International Atomic Energy Agency, an adult male can eat at least 10 g of Prussian blue per day without serious harm. The U. S. Prussian blue is a common stain used by pathologists to detect the presence of iron in biopsy specimens. The original stain formula, known historically as Perls Prussian blue after its inventor, German pathologist Max Perls, used separate solutions of potassium ferrocyanide, iron deposits in tissue then form the purple Prussian blue dye in place, and are visualized as blue or purple deposits. The formula is known as Perls Prussian blue and as Perls Prussian blue
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Lipid
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In biology, lipids comprise a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, triglycerides, phospholipids, and others. The main biological functions of lipids include storing energy, signaling, lipids have applications in the cosmetic and food industries as well as in nanotechnology. Biological lipids originate entirely or in part from two types of biochemical subunits or building-blocks, ketoacyl and isoprene groups. Although the term lipid is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides, lipids also encompass molecules such as fatty acids and their derivatives, as well as other sterol-containing metabolites such as cholesterol. Although humans and other mammals use various biosynthetic pathways both to break down and to synthesize lipids, some essential lipids cannot be made this way, the word lipid stems etymologically from the Greek lipos. The fatty acid structure is one of the most fundamental categories of biological lipids, the carbon chain, typically between four and 24 carbons long, may be saturated or unsaturated, and may be attached to functional groups containing oxygen, halogens, nitrogen, and sulfur. If a fatty acid contains a double bond, there is the possibility of either a cis or trans geometric isomerism, cis-double bonds cause the fatty acid chain to bend, an effect that is compounded with more double bonds in the chain. This in turn plays an important role in the structure and function of cell membranes, most naturally occurring fatty acids are of the cis configuration, although the trans form does exist in some natural and partially hydrogenated fats and oils. Examples of biologically important fatty acids include the eicosanoids, derived primarily from arachidonic acid and eicosapentaenoic acid, that include prostaglandins, leukotrienes, docosahexaenoic acid is also important in biological systems, particularly with respect to sight. Other major lipid classes in the fatty acid category are the fatty esters, fatty esters include important biochemical intermediates such as wax esters, fatty acid thioester coenzyme A derivatives, fatty acid thioester ACP derivatives and fatty acid carnitines. The fatty amides include N-acyl ethanolamines, such as the cannabinoid neurotransmitter anandamide, glycerolipids are composed of mono-, di-, and tri-substituted glycerols, the best-known being the fatty acid triesters of glycerol, called triglycerides. The word triacylglycerol is sometimes used synonymously with triglyceride, in these compounds, the three hydroxyl groups of glycerol are each esterified, typically by different fatty acids. Because they function as a store, these lipids comprise the bulk of storage fat in animal tissues. The hydrolysis of the bonds of triglycerides and the release of glycerol. Additional subclasses of glycerolipids are represented by glycosylglycerols, which are characterized by the presence of one or more sugar residues attached to glycerol via a glycosidic linkage, examples of structures in this category are the digalactosyldiacylglycerols found in plant membranes and seminolipid from mammalian sperm cells. Glycerophospholipids, usually referred to as phospholipids, are ubiquitous in nature and are key components of the bilayer of cells, as well as being involved in metabolism. Neural tissue contains high amounts of glycerophospholipids, and alterations in their composition has been implicated in various neurological disorders. Examples of glycerophospholipids found in biological membranes are phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine, the major sphingoid base of mammals is commonly referred to as sphingosine
34.
Sudan stain
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Sudan stains and Sudan dyes are synthetic organic compounds that are used as dyes for various plastics and are also used to stain sudanophilic biological samples, usually lipids. Sudan II, Sudan III, Sudan IV, Oil Red O, Sudan dyes have high affinity to fats, therefore they are used to demonstrate triglycerides, lipids, and lipoproteins. Alcoholic solutions of Sudan dyes are used, however pyridine solutions can be used in some situations as well. Sudan stain test is used to determine the level of fecal fat to diagnose steatorrhea. Normally a stool sample should show only a few drops of red-orange stained fat under the microscope, the method is only semiquantitative but, due to its simplicity, it is used for screening. Since they are characteristically oil-and fat-soluble, Sudan dyes are useful for dying plastics and fabrics. Sudan dyes I-IV and Sudan Red G consist of arylazo-substituted naphthols and this finding has led to controversy because some Sudan dyes are carcinogenic in rats
35.
Sudan II
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Sudan II is a lysochrome azo dye used for staining of triglycerides in frozen sections, and some protein bound lipids and lipoproteins on paraffin sections. It has the appearance of red powder with melting point 156–158 °C, other common names include Solvent Orange 7 and Color Index No,12140. Other names include, A F Red No,5, Brasilazina Oil Scarlet 6G, Brilliant Oil Scarlet B, Calco Oil Scarlet BL, Ceres Orange RR Cerisol Scarlet G, Cerotinscharlach G, EINECS 221-490-4, Ext D & C Red No. 14, Fast Oil Orange II, Fat Red, Fat Scarlet 2G,5, Resin Scarlet 2R, Resoform Orange R, Rot B, Rot GG fettloeslich, Solvent Orange 7, Somalia Orange 2R, Somalia Orange A2R, Sudan ax, Sudan Orange. Sudan Orange RPA, Sudan Orange RRA, Sudan Red, Sudan Scarlet 6G, Sudan X, UNII-8C1M5O3ECT, Waxakol vermilion, in industry, it is used to color nonpolar substances like oils, fats, waxes, greases, various hydrocarbon products, and acrylic emulsions. It was used a food dye under the designation FD&C Red 32 in the US until the FDA banned its use in food in 1956 due to toxicity
36.
Sudan III
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Sudan III is a lysochrome diazo dye. It is structurally related to azobenzene and it is used to color nonpolar calamaro substances like oils, fats, waxes, greases, various hydrocarbon products, and acrylic emulsions. The concentration required by IRS is an equivalent of 3.9 pounds per 1000 barrels, or 11.13 mg/l, of Solvent Red 26 in solid form. It is also used to dye some hydraulic fluids and some other hydrocarbons, Sudan III is a dye used for Sudan staining. Similar dyes include Oil Red O, Sudan IV, and Sudan Black B and they are used for staining of triglycerides in frozen sections, and some protein bound lipids and lipoproteins on paraffin sections. It has the appearance of reddish brown crystals and a maximum absorption at 507 nm and its other names are Sudan Red BK, Fat Ponceau G, Cerasin Red, C. I. 26100, Solvent Red 23, Sudan Red, Sudan Red III, Sudan V, Sudan Red B, Sudan G, Scarlet B, Sudan I, Sudan III, and Sudan IV have been classified as category 3 carcinogens by the International Agency for Research on Cancer. Its risk and safety phrases are S22-S24/S25, whitehouse Station, NJ, USA Edward Gurr. Synthetic Dyes in Biology, Medicine and Chemistry
37.
Sudan IV
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Sudan IV is a lysochrome diazo dye used for the staining of lipids, triglycerides and lipoproteins on frozen paraffin sections. It has the appearance of reddish brown crystals with melting point 199 °C, Sudan IV is one of the dyes used for Sudan staining. Similar dyes include Oil Red O, Sudan III, and Sudan Black B, staining is an important biochemical technique, offering the ability to visually qualify the presence of the fatty compound of interest without isolating it. For staining purposes Sudan IV can be made up in propylene glycol, alternatively, authors have reported using the dye saturated in isopropyl alcohol, 95% ethanol, or 0. 05% by weight in acetone, ethanol, water. The idea is to use a moderately apolar solvent to solubilize the dye allowing it to partition into the highly apolar fat without the solvent solubilizing the fat to be stained. Sudan I, Sudan III, and Sudan IV have been classified as category 3 carcinogens by the International Agency for Research on Cancer, in its purified form it is called Biebrich scarlet R, which should not be confused with the water-soluble Biebrich scarlet. In industry, it is used to color nonpolar substances like oils, fats, waxes, greases, various hydrocarbon products, and acrylic emulsions. Sudan IV is also used in United Kingdom as a dye to dye lower-taxed heating oil. As a food dye, Sudan IV is considered an illegal dye, mainly because of its effect over a long period of time. It was ruled unsafe in the 1995 food safety regulations report
