SUMMARY / RELATED TOPICS

Placenta

The placenta is a temporary organ that connects the developing fetus via the umbilical cord to the uterine wall to allow nutrient uptake, thermo-regulation, waste elimination, gas exchange via the mother's blood supply. Placentas are a defining characteristic of placental mammals, but are found in marsupials and some non-mammals with varying levels of development; the placenta functions as a fetomaternal organ with two components: the fetal placenta, which develops from the same blastocyst that forms the fetus, the maternal placenta, which develops from the maternal uterine tissue. It metabolizes a number of substances and can release metabolic products into maternal or fetal circulations; the placenta is expelled from the body upon birth of the fetus. The word placenta comes from the Latin word for a type of cake, from Greek πλακόεντα/πλακοῦντα plakóenta/plakoúnta, accusative of πλακόεις/πλακούς plakóeis/plakoús, "flat, slab-like", in reference to its round, flat appearance in humans; the classical plural is placentae, but the form placentas is common in modern English and has the wider currency at present.

Although all mammalian placentae have the same functions, there are important differences in structure and function in different groups of mammals. For example, bovine and canine placentae are different at the both gross and the microscopic levels. Placentae of these species differ in their ability to provide maternal immunoglobulins to the fetus. Placental mammals, such as humans, have a chorioallantoic placenta that forms from the chorion and allantois. In humans, the placenta averages 22 cm in length and 2–2.5 cm in thickness, with the center being the thickest, the edges being the thinnest. It weighs 500 grams, it has crimson color. It connects to the fetus by an umbilical cord of 55–60 cm in length, which contains two umbilical arteries and one umbilical vein; the umbilical cord inserts into the chorionic plate. Vessels branch out over the surface of the placenta and further divide to form a network covered by a thin layer of cells; this results in the formation of villous tree structures. On the maternal side, these villous tree structures are grouped into lobules called cotyledons.

In humans, the placenta has a disc shape, but size varies vastly between different mammalian species. The placenta takes a form in which it comprises several distinct parts connected by blood vessels; the parts, called lobes, may number two, four, or more. Such placentas are described as bilobed/bilobular/bipartite, trilobed/trilobular/tripartite, so on. If there is a discernible main lobe and auxiliary lobe, the latter is called a succenturiate placenta. Sometimes the blood vessels connecting the lobes get in the way of fetal presentation during labor, called vasa previa. About 20,000 protein coding genes are expressed in human cells and 70% of these genes are expressed in the normal mature placenta; some 350 of these genes are more expressed in the placenta and fewer than 100 genes are placenta specific. The corresponding specific proteins are expressed in trophoblasts and have functions related to female pregnancy. Examples of proteins with elevated expression in placenta compared to other organs and tissues are PEG10 and the cancer testis antigen PAGE4 and expressed in cytotrophoblasts, CSH1and KISS1 expressed in syncytiotrophoblasts, PAPPA2 and PRG2 expressed in extravillous trophoblasts.

The placenta begins to develop upon implantation of the blastocyst into the maternal endometrium. The outer layer of the blastocyst becomes the trophoblast, which forms the outer layer of the placenta; this outer layer is divided into two further layers: the underlying cytotrophoblast layer and the overlying syncytiotrophoblast layer. The syncytiotrophoblast is a multinucleated continuous cell layer that covers the surface of the placenta, it forms as a result of differentiation and fusion of the underlying cytotrophoblast cells, a process that continues throughout placental development. The syncytiotrophoblast, thereby contributes to the barrier function of the placenta; the placenta grows throughout pregnancy. Development of the maternal blood supply to the placenta is complete by the end of the first trimester of pregnancy week 14. In preparation for implantation of the blastocyst, the endometrium undergoes decidualization. Spiral arteries in the decidua are remodeled so that they become less convoluted and their diameter is increased.

The increased diameter and straighter flow path both act to increase maternal blood flow to the placenta. There is high pressure as the maternal blood fills intervillous space through these spiral arteries which bathe the fetal villi in blood, allowing an exchange of gases to take place. In humans and other hemochorial placentals, the maternal blood comes into direct contact with the fetal chorion, though no fluid is exchanged; as the pressure decreases between pulses, the deoxygenated blood flows back through the endometrial veins. Maternal blood flow is 600–700 ml/min at term; this begins at day 5 - day 12 Deoxygenated fetal blood passes through umbilical arteries to the placenta. At the junction of umbilical cord and placenta, the umbilical arteries branch radially to form chorionic arteries. Chorionic arteries, in turn, branch into cotyledon arteries. In the villi, these vessels branch to form an extensive arterio-capillary-venous system, bringing the fetal blood close to the maternal blood.

Kiribati women's national football team

The Kiribati women's national football team is the women's national football team of Kiribati and is controlled by the Kiribati Islands Football Association. Kiribati is not a member of FIFA or of the Oceania Football Confederation, is therefore not eligible to enter the FIFA Women's World Cup. Kiribati is a member of ConIFA, though there have been no women's tournaments to date for the side to participate in. Kiribati have played 6 international matches up to July 2019 where they scored 2 goals and conceded 38 in the Football at the 2003 South Pacific Games – Women's tournament. Kiribati's first match took place in Nausori, Fiji on 30 June 2003 when they played Papua New Guinea, losing 13–0 in a South Pacific Games match; the side have never won a match but came close when they lost 2–1 to Tonga on 7 July 2003 in the South Pacific Games in Fiji. Kiribati's only two goals in the 2003 Pacific games were scored by Moaniti Teuea versus Tonga in the 48th minute, and versus Tahiti in the 10th minuteOn 6 May 2016, Kiribati was formally accepted as the newest member of ConIFA, becoming the first Oceanic member to join the federation.

As of July 2019, Kiribati's women's team have played no games under ConIFA. 2003 – Round 1 2007 to 2019 – Did not enter Squad selected for the 2003 Pacific Games. Kiribati national football team Kiribati women's results at rsssf

Trigeminal ganglion

The trigeminal ganglion is a sensory ganglion of the trigeminal nerve that occupies a cavity in the dura mater, covering the trigeminal impression near the apex of the petrous part of the temporal bone. It is somewhat crescent-shaped, with its convexity directed forward: Medially, it is in relation with the internal carotid artery and the posterior part of the cavernous sinus; the motor root runs in front of and medial to the sensory root, passes beneath the ganglion. The greater superficial petrosal nerve lies underneath the ganglion; the ganglion receives, on its medial side, filaments from the carotid plexus of the sympathetic. It gives off minute branches to the tentorium cerebelli, to the dura mater in the middle fossa of the cranium. From its convex border, directed forward and lateralward, three large nerves proceed, viz. the ophthalmic and mandibular. The ophthalmic and maxillary consist of sensory fibers. After recovery from a primary herpes infection, the virus is not cleared from the body, but rather lies dormant in a non-replicating state within the trigeminal ganglion.

Herpes Labialis may follow from primary herpes infection/herpetic gingivostomatitis The trigeminal ganglion is damaged, by infection or surgery, in Trigeminal trophic syndrome. Trigeminal trophic syndrome causes paresthesias and anesthesia, which may lead to erosions of the nasal ala; the thermocoagulation or injection of glycerol into the trigeminal ganglion has been used in the treatment of trigeminal neuralgia. In rodents, the trigeminal ganglion is important as it is the first part of the pathway from the whiskers to the brain. Cell bodies of the whisker primary afferents are found here; these afferents are mechanoreceptor cells that fire in response to whisker deflection. There are around 26,000-43,000 cell bodies in rodent Trigeminal ganglion, it is possible that there are two distinct populations of cells having and adapting responses to stimuli. It is found at the base of the skull and projects to trigeminal brain stem areas including principalis, spinal trigeminal nucleus and caudalis.

This article incorporates text in the public domain from page 886 of the 20th edition of Gray's Anatomy Diagram at University of Manitoba Diagram at frca.co.uk MedEd at Loyola grossanatomy/dissector/labs/h_n/cranium/cn3_1a.htm ancil-484 at NeuroNames cranialnerves at The Anatomy Lesson by Wesley Norman