The ovary is an organ found in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary found on each side of the body; the ovaries secrete hormones that play a role in the menstrual cycle and fertility. The ovary progresses through many stages beginning in the prenatal period through menopause, it is an endocrine gland because of the various hormones that it secretes. The ovaries are considered the female gonads; each ovary is whitish in color and located alongside the lateral wall of the uterus in a region called the ovarian fossa. The ovarian fossa is the region, bounded by the external iliac artery and in front of the ureter and the internal iliac artery; this area is about 4 cm x 3 cm x 2 cm in size. The ovaries are surrounded by a capsule, have an outer cortex and an inner medulla; the capsule is known as the tunica albuginea. Ovulation occurs in one of the two ovaries releasing an egg each menstrual cycle.
The side of the ovary closest to the fallopian tube is connected to it by infundibulopelvic ligament, the other side points downwards attached to the uterus via the ovarian ligament. Other structures and tissues of the ovaries include the hilum; the ovaries lie within the peritoneal cavity, on either side of the uterus, to which they are attached via a fibrous cord called the ovarian ligament. The ovaries are uncovered in the peritoneal cavity but are tethered to the body wall via the suspensory ligament of the ovary, a posterior extension of the broad ligament of the uterus; the part of the broad ligament of the uterus that covers the ovary is known as the mesovarium. The ovarian pedicle is made up part of the fallopian tube, ovarian ligament, ovarian blood vessels; the surface of the ovaries is covered with membrane consisting of a lining of simple cuboidal-to-columnar shaped mesothelium, called the germinal epithelium. The outer layer is the ovarian cortex, consisting of stroma in between them.
Included in the follicles are the cumulus oophorus, membrana granulosa, corona radiata, zona pellucida, primary oocyte. Theca of follicle and liquor folliculi are contained in the follicle. In the cortex is the corpus luteum derived from the follicles; the innermost layer is the ovarian medulla. It can be hard to distinguish between the cortex and medulla, but follicles are not found in the medulla. Follicular cells are flat epithelial cells that originate from surface epithelium covering the ovary, are surrounded by Granulosa cells - that have changed from flat to cuboidal and proliferated to produce a stratified epithelium Other GametesThe ovary contains blood vessels and lymphatics. At puberty, the ovary begins to secrete increasing levels of hormones. Secondary sex characteristics begin to develop in response to the hormones; the ovary changes function beginning at puberty. Since the ovaries are able to regulate hormones, they play an important role in pregnancy and fertility; when egg cells, are released from the Fallopian tube, a variety of feedback mechanisms stimulate the endocrine system which cause hormone levels to change.
These feedback mechanisms are controlled by the hypothalamus and pituitary gland. Messages from the hypothalamus are sent to the pituitary gland. In turn, the pituitary gland releases hormones to the ovaries. From this signaling, the ovaries release their own hormones; the ovaries are periodical release of egg cells, the female gametes. In the ovaries, the developing egg cells mature in the fluid-filled follicles. Only one oocyte develops at a time, but others can mature simultaneously. Follicles are composed of different types and number of cells according to the stage of their maturation, their size is indicative of the stage of oocyte development; when the oocyte finishes its maturation in the ovary, a surge of luteinizing hormone secreted by the pituitary gland stimulates the release of the oocyte through the rupture of the follicle, a process called ovulation. The follicle remains functional and reorganizes into a corpus luteum, which secretes progesterone in order to prepare the uterus for an eventual implantation of the embryo.
At maturity, ovaries secrete estrogen, testosterone and progesterone. In women, fifty percent of testosterone is produced by the ovaries and adrenal glands and released directly into the blood stream. Estrogen is responsible for the appearance of secondary sex characteristics for females at puberty and for the maturation and maintenance of the reproductive organs in their mature functional state. Progesterone prepares the uterus for pregnancy, the mammary glands for lactation. Progesterone functions with estrogen by promoting menstrual cycle changes in the endometrium; as women age, they experience a decline in reproductive performance leading to menopause. This decline is tied to a decline in the number of ovarian follicles. Although about 1 million oocytes are present at birth in the human ovary, only about 500 of these ovulate, the rest are wasted; the decline in ovarian reserve appears to occur at a increasing rate with age, leads to nearly complete exhaustion of the reserve by about age 52.
As ovarian reserve and fertility decline with age, there is a parallel increase in pregnancy failure and meiotic errors resulting in chromosomally abnormal conceptions. The ovarian reserve and fertility perform optimally around 20–30 years of age. Around 45 years of age, the menstrual cycle begins to change and the follicle pool decreases significant
The World Monuments Watch is a flagship advocacy program of the New York-based private non-profit organization World Monuments Fund that calls international attention to cultural heritage around the world, threatened by neglect, conflict, or disaster. Every two years, it publishes a select list known as the Watch List of Endangered Sites that are in urgent need of preservation funding and protection; the sites are nominated by governments, conservation professionals, site caretakers, non-government organizations, concerned individuals, others working in the field. An independent panel of international experts select 100 candidates from these entries to be part of the Watch List, based on the significance of the sites, the urgency of the threat, the viability of both advocacy and conservation solutions. For the succeeding two-year period until a new Watch List is published, these 100 sites can avail grants and funds from the WMF, as well as from other foundations, private donors, corporations by capitalizing on the publicity and attention gained from the inclusion on the Watch List.
The 2012 Watch List was published on 5 October 2011. The following countries/territories have multiple sites entered on the 2012 Watch List, listed by the number of sites
The Hanover Center Historic District encompasses the historic town center of Hanover, Massachusetts. Established in 1721, the town center includes the town hall and church, as well as its first cemetery and the c. 1700 Stetson House, one of its oldest buildings. The district was listed on the National Register of Historic Places in 1996; the area, now Hanover was settled around 1700 as part of Scituate. Much of its land had been awarded to Cornet Robert Stetson in 1634, it was his son Benjamin who built the house c. 1700 standing on the south side of the town center. Enlarged about 1716, it was here that early meetings were held that led to the town's incorporation in 1727. In that year, the town cemetery was laid out, its first meeting house was built, where the present First Congregational Church stands. Over the 19th and early 20th centuries, the center acquired the trappings of a modest New England town center, including its town hall and library; the historic district includes seven properties located around the junction of Hanover Street with Main and Silver Streets, near the geographic center of the town.
On the south side of Hanover Street stand, the Stetson House, now a museum of the local historical society, the Curtis Free Library, the Italianate town hall. The First Congregational Church occupies a prominent location on what is now an island surrounded by the three roadways, the cemetery is located to its north. East of the church is the Colonial Revival Sylvester School, built in 1927 as the town's first public high school. West of the church stands its parsonage house, built about 1855. National Register of Historic Places listings in Plymouth County, Massachusetts