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Corpus luteum

 
Corpus Luteum

 
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Corpus luteum
 
 
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The corpus luteum (Latin
Latin

Latin is an Italic language, historically spoken in Latium and Ancient Rome. Through the Military history of the Roman Empire, Latin spread throughout the Mediterranean and a large part of Europe....
 for "yellow body") (plural corpora lutea) is a temporary endocrine structure in mammals, involved in production of progestogen, which is needed to maintain pregnancy.

corpus develops from an ovarian follicle
Ovarian follicle

Ovarian follicle is the basic unit of female reproductive biology and is composed of roughly spherical aggregations of cell s found in the ovary....
 during the luteal phase
Luteal phase

The luteal phase is the latter phase of the menstrual cycle or the estrous cycle . It begins with the formation of the corpus luteum and ends in either pregnancy or luteolysis....
 of the menstrual cycle
Menstrual cycle

The menstrual cycle is a recurring cycle of physiology changes that occurs in reproductive-age females. Overt menstruation occurs primarily in humans and close evolutionary relatives such as chimpanzees....
 or estrous cycle
Estrous cycle

The oestrous cycle comprises the recurring physiology changes that are induced by sexual reproduction hormones in most mammalian placental females....
, following the release of a secondary oocyte from the follicle during ovulation
Ovulation

Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum that participates in reproduction....
. The follicle first forms a corpus hemorrhagicum
Corpus hemorrhagicum

The corpus hemorrhagicum is a temporary structure formed immediately after ovulation from the ovarian follicle. After the trauma heals, the subsequent structure is called the corpus luteum ...
 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.






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The corpus luteum (Latin
Latin

Latin is an Italic language, historically spoken in Latium and Ancient Rome. Through the Military history of the Roman Empire, Latin spread throughout the Mediterranean and a large part of Europe....
 for "yellow body") (plural corpora lutea) is a temporary endocrine structure in mammals, involved in production of progestogen, which is needed to maintain pregnancy.

Development and structure

The corpus develops from an ovarian follicle
Ovarian follicle

Ovarian follicle is the basic unit of female reproductive biology and is composed of roughly spherical aggregations of cell s found in the ovary....
 during the luteal phase
Luteal phase

The luteal phase is the latter phase of the menstrual cycle or the estrous cycle . It begins with the formation of the corpus luteum and ends in either pregnancy or luteolysis....
 of the menstrual cycle
Menstrual cycle

The menstrual cycle is a recurring cycle of physiology changes that occurs in reproductive-age females. Overt menstruation occurs primarily in humans and close evolutionary relatives such as chimpanzees....
 or estrous cycle
Estrous cycle

The oestrous cycle comprises the recurring physiology changes that are induced by sexual reproduction hormones in most mammalian placental females....
, following the release of a secondary oocyte from the follicle during ovulation
Ovulation

Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum that participates in reproduction....
. The follicle first forms a corpus hemorrhagicum
Corpus hemorrhagicum

The corpus hemorrhagicum is a temporary structure formed immediately after ovulation from the ovarian follicle. After the trauma heals, the subsequent structure is called the corpus luteum ...
 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
Oocyte

An oocyte, ovocyte, or rarely ocyte, is a female gametocyte or germ cell involved in biological reproduction. In other words, it is an immature ovum, or ovum cell....
 (later the zygote
Zygote

A zygote is a cell that is the result of fertilization. That is, two ploidy cells—usually an ovum from a female and a sperm cell from a male—merge into a single ploidy cell called the zygote ....
) traverses the Fallopian tube
Fallopian tube

The Fallopian tubes, named after Gabriel Fallopius , also known as oviducts, uterine tubes, and salpinges are two very fine tubes lined with cilia epithelia, leading from the ovaries of female mammals into the uterus....
 into the uterus
Uterus

The uterus is a major female hormone-responsive reproductive sex organ of most mammals, including humans. It is within the uterus that the fetus develops during gestation....
, the corpus luteum remains in the ovary
Ovary

The ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in females are homology to testicle in males, in that they are both gonads and endocrine glands....
.

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 mm to 5 mm in diameter.

Its cells develop from the follicular cells surrounding the ovarian follicle
Ovarian follicle

Ovarian follicle is the basic unit of female reproductive biology and is composed of roughly spherical aggregations of cell s found in the ovary....
:

Source Becomes Secretion >- | The granulosa cells the inner granulosa lutein layer progesterone
Progesterone

Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species. Progesterone belongs to a class of hormones called progestogens, and is the major naturally occurring human progestogen....
 |- | Theca cells 		the outer theca lutein layer estrogen
Estrogen

Estrogens are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone....
, androgens


Function

The corpus luteum is essential for establishing and maintaining pregnancy in females.

In the ovary, the corpus luteum secretes estrogen
Estrogen

Estrogens are a group of steroid compounds, named for their importance in the estrous cycle, and functioning as the primary female sex hormone....
s and progesterone
Progesterone

Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy and embryogenesis of humans and other species. Progesterone belongs to a class of hormones called progestogens, and is the major naturally occurring human progestogen....
, which are steroid hormone
Steroid hormone

Steroid hormones are steroids that act as hormones. Steroid hormones can be grouped into five groups by the receptor s to which they bind: glucocorticoids, mineralocorticoids, androgens, estrogens, and progestagens....
s responsible for the thickening of the endometrium
Endometrium

The endometrium is the inner membrane of the mammalian uterus....
 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
Corpus albicans

The corpus albicans is the regressed form of the corpus luteum. As the corpus luteum is being broken down by macrophages, fibroblasts lay down type I collagen, forming the corpus albicans....
, which is a mass of fibrous scar
Scar

Scars are areas of fibrous biological tissue that replace normal skin after injury. A scar results from the biologic process of wound repair in the skin and other biological tissue of the body....
 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
Menstrual cycle

The menstrual cycle is a recurring cycle of physiology changes that occurs in reproductive-age females. Overt menstruation occurs primarily in humans and close evolutionary relatives such as chimpanzees....
). In an estrus cycle, the lining degenerates back to normal size.

When egg is fertilized

If the egg is fertilized and implantation
Implantation

Implantation is an event that occurs early in pregnancy in which the embryo adheres to the wall of uterus. At this stage of prenatal development, the embryo is a blastocyst....
 occurs, the trophoblast
Trophoblast

Trophoblasts are cells forming the outer layer of a blastocyst, which provide nutrients to the embryo and develop into a large part of the placenta....
 cells of the blastocyst
Blastocyst

The blastocyst is the structure formed in early embryogenesis, after the formation of the blastocoel, but before implantation.It possesses an inner cell mass, or inner cell mass which subsequently forms the embryo proper, and an outer layer of cells, or trophoblast which later forms the placenta....
 secrete the hormone human chorionic gonadotropin
Human chorionic gonadotropin

Human chorionic gonadotropin is a glycoprotein hormone produced in pregnancy that is made by the the developing embryo soon after Conception and later by the syncytiotrophoblast ....
 (hCG, or a similar hormone in other species).

Human chorionic gonadotropin 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
Blood vessel

The blood vessels are the part of the circulatory system that transport blood throughout the body. There are three major types of blood vessels: the artery, which carry the blood away from the heart, the capillary, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins, which carry blood from...
s in which the zygote
Zygote

A zygote is a cell that is the result of fertilization. That is, two ploidy cells—usually an ovum from a female and a sperm cell from a male—merge into a single ploidy cell called the zygote ....
(s) can develop. From this point on, the corpus luteum is called the corpus luteum graviditatis.

The introduction of prostaglandin
Prostaglandin

A prostaglandin is any member of a group of lipid compounds that are derived enzymatically from fatty acids and have important functions in the animal body....
s at this point causes the degeneration of the corpus luteum and the abortion
Abortion

An abortion is the termination of a pregnancy by the removal or expulsion of an embryo or fetus from the uterus, resulting in or caused by its death....
 of the fetus
Fetus

A fetus is a developing mammal or other viviparous vertebrate, after the embryonic stage and before childbirth. The plural is fetuses, or sometimes feti....
. However, in placental animals such as humans, the placenta
Placenta

The placenta or afterbirth is a highly vascularized ephemeral organ present in Placentalia vertebrates that connects the developing fetal tissues to the uterine wall....
 eventually takes over progesterone production and the corpus luteum degrades into a corpus albicans
Corpus albicans

The corpus albicans is the regressed form of the corpus luteum. As the corpus luteum is being broken down by macrophages, fibroblasts lay down type I collagen, forming the corpus albicans....
 without embryo/fetus loss.

Additional images


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