World Library  
Flag as Inappropriate
Email this Article

Ovarian

Article Id: WHEBN0001126707
Reproduction Date:

Title: Ovarian  
Author: World Heritage Encyclopedia
Language: English
Subject: Bleeding, Teratoma, ICD-10 Chapter IV: Endocrine, nutritional and metabolic diseases, List of people from Columbus, Ohio
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Ovarian

For ovary as part of plants, see Ovary (botany).
"Ovaria" redirects here. This is also a proposed section and a synonym of Solanum.
Ovary
Blood supply of the human female reproductive organs. The left ovary is visible above the label "ovarian arteries".
Latin ovarium
Gray's subject #266 1254
Artery ovarian artery, uterine artery
Vein ovarian vein
Nerve ovarian plexus
Lymph Paraaortic lymph node
MeSH Ovary
Dorlands/Elsevier Ovary

The ovary (From Latin: ovarium, literally “egg” or “nut”) is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in female individuals are analogous to testes in male individuals, in that they are both gonads and endocrine glands.

Human anatomy

Each ovary is pearly-white in color and located alongside the lateral wall of the pelvis in a region called the ovarian fossa. The fossa usually lies beneath the external iliac artery and in front of the ureter and the internal iliac artery. It is about 4 cm x 3 cm x 2 cm in size.[1]

Usually each ovary takes turns releasing an egg every month; however, if there was a case where one ovary was absent or dysfunctional then the other ovary would continue providing eggs to be released.

Hormones

Ovaries secrete estrogen, testosterone[2][3][4][5] and progesterone. In women, fifty per cent of testosterone is produced by the ovaries and adrenal glands and released directly into the blood stream.[6] 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, and the mammary glands for lactation. Progesterone functions with estrogen by promoting menstrual cycle changes in the endometrium.

Ligaments

In the human the paired ovaries lie within the pelvic 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. The part of the broad ligament of the uterus that covers the ovary is known as the mesovarium. Thus, the ovary is the only organ in the human body which is totally invaginated into the peritonium, making it the only intraperitoneal organ (not to be confused with interperitoneal).

Extremities

There are two extremities to the ovary:

Histology

  • Follicular cells flat epithelial cells that originate from surface epithelium covering the ovary
  • Granulosa cells - surrounding follicular cells have changed from flat to cuboidal and proliferated to produce a stratified epithelium
  • Gametes[7]

In other animals

Ovaries of some kind are found in the female reproductive system of many animals that employ sexual reproduction, including invertebrates. However, they develop in a very different way in most invertebrates than they do in vertebrates, and are not truly homologous.[8]

Many of the features found in human ovaries are common to all vertebrates, including the presence of follicular cells, tunica albuginea, and so on. However, many species produce a far greater number of eggs during their lifetime than do humans, so that, in fish and amphibians, there may be hundreds, or even millions of fertile eggs present in the ovary at any given time. In these species, fresh eggs may be developing from the germinal epithelium throughout life. Corpora lutea are found only in mammals, and in some elasmobranch fish; in other species, the remnants of the follicle are quickly resorbed by the ovary. In birds, reptiles, and monotremes, the egg is relatively large, filling the follicle, and distorting the shape of the ovary at maturity.[8]

Amphibians and reptiles have no ovarian medulla; the central part of the ovary is a hollow, lymph-filled space. The ovary of teleosts is also often hollow, but in this case, the eggs are shed into the cavity, which opens into the oviduct.[8]

Although most normal female vertebrates have two ovaries, this is not the case in all species. In most birds and in platypuses, the right ovary never matures, so that only the left is functional. (Exceptions include the Kiwi and some, but not all raptors, in which both ovaries persist.[9][10]) In some elasmobranchs, only the right ovary develops fully. In the primitive jawless fish, and some teleosts, there is only one ovary, formed by the fusion of the paired organs in the embryo.[8]

Cryopreservation

Diseases

Ovarian diseases can be classified as endocrine disorders or as a disorders of the reproductive system.

If the egg fails to release from the follicle in the ovary an ovarian cyst may form. Small ovarian cysts are common in healthy women. Some women have more follicles than usual (polycystic ovary syndrome), which inhibits the follicles to grow normally and this will cause cycle irregularities.

Ovarian aging

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 (about 0.05%) of these ovulate, and the rest are wasted. The decline in ovarian reserve appears to occur at a constantly increasing rate with age,[15] and leads to nearly complete exhaustion of the reserve by about age 52. As ovarian reserve and fertility decline with age, there is also a parallel increase in pregnancy failure and meiotic errors resulting in chromosomally abnormal conceptions.

Women with an inherited mutation in the DNA repair gene BRCA1 undergo menopause prematurely,[16] suggesting that naturally occurring DNA damages in oocytes are repaired less efficiently in these women, and this inefficiency leads to early reproductive failure. The BRCA1 protein plays a key role in a type of DNA repair termed homologous recombinational repair that is the only known cellular process that can accurately repair DNA double-strand breaks. Titus et al.[17] showed that DNA double-strand breaks accumulate with age in humans and mice in primordial follicles. Primodial follicles contain oocytes that are at an intermediate (prophase I) stage of meiosis. Meiosis is the general process in eukaryotic organisms by which germ cells are formed, and it is likely an adaptation for removing DNA damages, especially double-strand breaks, from germ line DNA.[18] (see Meiosis and Origin and function of meiosis). Homologous recombinational repair is especially promoted during meiosis. Titus et al.[17] also found that expression of 4 key genes necessary for homologous recombinational repair of DNA double-strand breaks (BRCA1, MRE11, RAD51 and ATM) decline with age in the oocytes of humans and mice. They hypothesized that DNA double-strand break repair is vital for the maintenance of oocyte reserve and that a decline in efficiency of repair with age plays a key role in ovarian aging.

Other conditions include

Additional Images

See also

References

External links

  • From the American Medical Association
  • Merck Online Medical Library: Female Reproductive System

Template:Animal anatomy

This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.