View source for Corpus luteum

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  Caption      = x |
  Image2       = Gray1163.png |
  Caption2     = Section of the ovary. 1. Outer covering. 1’. Attached border. 2. Central stroma. 3. Peripheral stroma. 4. Bloodvessels. 5. Vesicular follicles in their earliest stage. 6, 7, 8. More advanced follicles. 9. An almost mature follicle. 9’. Follicle from which the ovum has escaped. 10. '''Corpus luteum'''. |
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==Overview==
The '''corpus luteum''' (Latin for "yellow body") (plural '''corpora lutea''') is a temporary [[endocrine]] structure in mammals, involved in the production of the [[progestogens]] which are needed for the maintenance of a pregnancy.

==Development and structure==
The ''corpus luteum'' develops from an [[ovarian follicle]] during the [[luteal phase]] of the [[menstrual cycle]] or [[estrous cycle]], following the release of a mature [[ovum]] (egg) from the follicle during [[ovulation]]. The follicle first forms a [[corpus hemorrhagicum]] before it becomes a corpus luteum, but the term simply refers to the visible collection of blood left after rupture of the follicle, and has no functional significance. While the [[oocyte]] (later the [[zygote]]) traverses the [[Fallopian tube]] into the [[uterus]], the corpus luteum remains in the [[ovary]].

The corpus luteum is typically very large relative to the size of the ovary; in humans, the size of the structure ranges from under 2 cm to 6 cm in diameter. <ref>[http://www.drspock.com/article/0,1510,5335,00.html "Corpus Luteum Cyst of Pregnancy" at drspock.com]</ref> 

Its cells develop from the follicular cells surrounding the [[ovarian follicle]]:

{| class="wikitable"
| '''Source''' || '''Becomes''' || '''Secretion'''
 |- 
 | The [[granulosa]] cells || the inner ''granulosa lutein'' layer || [[progesterone]], [[estrogen]]
 |- 
 | [[Theca interna|Theca]] cells || the outer ''theca lutein'' layer  || [[progesterone]], [[androgens]]
|}

==Function==
It is essential for establishing and maintaining pregnancy in females.

In the ovary, the corpus luteum secretes [[estrogen]]s and [[progesterone]], which are [[steroid hormone]]s responsible for the thickening of the [[endometrium]] and its development and maintenance, respectively.  

===When egg is not fertilized===
If the egg is not fertilized, the corpus luteum stops secreting progesterone and decays (after approximately 14 days in humans). It then degenerates into a [[corpus albicans]], which is a mass of fibrous [[scar]] tissue. 

The uterine lining sloughs off without progesterone and is expelled through the vagina (in humans and some great apes, which go through a [[menstrual cycle]]). In an [[estrus cycle]] the lining degenerates back to normal size.

===When egg is fertilized===
If fertilized, however, the [[embryo]] secretes the hormone [[human chorionic gonadotropin]] (hCG) or a similar hormone in other species. 

This hormone signals the corpus luteum to continue progesterone secretion, thereby maintaining the thick lining (endometrium) of the uterus, and providing an area rich in [[blood vessel]]s in which the [[zygote]](s) can develop. From this point on, the corpus luteum is called the ''corpus luteum graviditatis''. 

The introduction of the hormone [[prostaglandin]] at this point causes the degeneration of the corpus luteum and the [[abortion]] of the [[fetus]]. However, in placental animals such as humans the [[placenta]] eventually takes over progesterone production and the corpus luteum degrades into a [[corpus albicans]] without embryo/fetus loss.

==Additional images==
<gallery>
 Image:Order_of_changes_in_ovary_svg.png|Order of changes in ovary
 Image:MenstrualCycle.png|Menstrual Cycle
</gallery>

==External links==
* {{BUHistology|18201loa}}
* {{SUNYAnatomyLabs|43|05|01|06}} - "The Female Pelvis: The Ovary"

==Reference==
<references/>

{{Female reproductive system}}
{{endocrine_system}}

[[Category:Histology]]
[[Category:Gynecology]]
[[Category:Reproductive system]]
[[Category:Endocrinology]]
[[Category:Overview complete]]


[[he:גופיף צהוב]]
[[de:Gelbkörper]]
[[fr:Corps jaune]]
[[lt:Geltonkūnis]]
[[mk:Жолто тело]]
[[ja:黄体]]
[[pl:Ciałko żółte]]
[[pt:Corpo lúteo]]
[[sv:Gulkropp]]

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