Endometrium
Uterus and uterine tubes. (Endometrium labeled at center right.)
Opened uterus with cat fetus in midgestation: 1 umbilicus, 2 amnion, 3 allantois, 4 Yolk sac, 5 developing marginal hematoma, 6 maternal part of placenta (endometrium)
Latin	tunica mucosa uteri
Gray's	subject #268 1262
MeSH	Endometrium
Dorlands/Elsevier	t_22/12832078

The endometrium is the inner membrane of the mammalian uterus. Image File history File linksMetadata Illu_cervix. ... Image File history File links Download high-resolution version (1082x1372, 164 KB) opened uterus with cat fetus in midgestation 1 umbilicus, 2 amnion, 3 allantois, 4 Yolk sac, 5 developing marginal hematoma, 6 maternal part of placenta (endometrium) File links The following pages on the English Wikipedia link to this... Trinomial name Felis catus Linnaeus, 1758 The cat (or domestic cat, house cat) is a small carnivorous mammal. ... This article or section does not cite its references or sources. ... For the alien race in Stephen Donaldsons The Gap Cycle, see Amnion (Gap Cycle). ... Allantois is a part of a developing animal embryo. ... The yolk sac is the first element seen in the gestational sac during pregnancy, usually at 5 weeks gestation. ... Hematoma on an elbow, nine days after a blood sample was taken Hematoma on a forearm, one day after repeated shocks A hematoma, or haematoma, is a collection of blood, generally the result of hemorrhage. ... The placenta is an ephemeral (temporary) organ present only in female placental vertebrates during gestation (pregnancy). ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... Medical Subject Headings (MeSH) is a huge controlled vocabulary (or metadata system) for the purpose of indexing journal articles and books in the life sciences. ... Elseviers logo. ... Orders Subclass Monotremata Monotremata Subclass Marsupialia Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Subclass Placentalia Xenarthra Dermoptera Desmostylia Scandentia Primates Rodentia Lagomorpha Insectivora Chiroptera Pholidota Carnivora Perissodactyla Artiodactyla Cetacea Afrosoricida Macroscelidea Tubulidentata Hyracoidea Proboscidea Sirenia The mammals are the class of vertebrate animals primarily characterized by the presence of mammary... The uterus or womb is the major female reproductive organ of most mammals, including humans. ...

Function

The endometrium functions as a lining for the uterus, preventing adhesions between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. During the menstrual cycle or estrous cycle, the endometrium grows to a thick, blood vessel rich, glandular tissue layer. This represents an optimal environment for the implantation of a blastocyst upon its arrival in the uterus. The myometrium is the middle layer of the uterine wall consisting of smooth muscle cells and supporting stromal and vascular tissue. ... Menstrual cycle The menstrual cycle is a recurring cycle of physiological changes in the females of some animal species that is associated with reproductive fertility. ... The estrous cycle (also oestrous cycle; originally derived from Latin oestrus) refers to the recurring physiologic changes that are induced by reproductive hormones in most mammalian placental females. ... The blastocyst is the structure formed in early mammalian embryogenesis, after the formation of the blastocele, but before implantation. ...

During pregnancy, the glands and blood vessels in the endometrium further increase in size and number. Vascular spaces fuse and become interconnected, forming the placenta, which supplies oxygen and nutrition to the embryo and fetus.:) A pregnant woman near the end of her term Pregnancy is the carrying of one or more embryos or fetuses by female mammals, including humans, inside their bodies. ... The arterial system The blood vessels are part of the circulatory system and function to transport blood throughout the body. ... The placenta is an ephemeral (temporary) organ present only in female placental vertebrates during gestation (pregnancy). ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... It has been suggested that embryology be merged into this article or section. ... A human fetus A fetus (or foetus, or fœtus – see below) is a developing mammal after the embryonic stage and before birth. ...

Cycle

The endometrial lining undergoes cyclic regeneration. Humans and the great apes display the menstrual cycle, whereas most other mammals are subject to an estrous cycle. In both cases, the endometrium initially proliferates under the influence of estrogen. However, once ovulation occurs, in addition to estrogen, the ovary will also start to produce progesterone. This changes the proliferative pattern of the endometrium to a secretory lining. Eventually, the secretory lining provides a hospitable environment for one or more blastocysts. Genera Subfamily Ponginae Pongo - Orangutans Gigantopithecus (extinct) Sivapithecus (extinct) Subfamily Homininae Gorilla - Gorillas Pan - Chimpanzees Homo - Humans Paranthropus (extinct) Australopithecus (extinct) Sahelanthropus (extinct) Ardipithecus (extinct) Kenyanthropus (extinct) Pierolapithecus (extinct) (tentative) The Hominids (Hominidae) are a biological family which includes humans, extinct species of humanlike creatures and the other great apes... Menstrual cycle The menstrual cycle is a recurring cycle of physiological changes in the females of some animal species that is associated with reproductive fertility. ... The estrous cycle (also oestrous cycle; originally derived from Latin oestrus) refers to the recurring physiologic changes that are induced by reproductive hormones in most mammalian placental females. ... Estriol. ... Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum (also known as an oocyte, female gamete, or casually, an egg) that participates in reproduction. ... Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. ...

If no blastocyst is detected, the progesterone level drops and the endometrial lining is either reabsorbed (estrous cycle) or shed (menstrual cycle). In the latter case, the process of shedding involves the breaking down of the lining, the tearing of small connective blood vessels, and the loss of the tissue and blood that had constituted it through the vagina. The entire process occurs over a period of several days. Menstruation may be accompanied by a series of uterine contractions; these help expel the menstrual endometrium. The vagina, (from Latin, literally sheath or scabbard ) is the tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. ...

In case of implantation, however, the endometrial lining is neither absorbed nor shed. Instead, it remains as decidua. The decidua becomes part of the placenta; it provides support and protection for the gestation. Decidua is the term for the uterine lining (endometrium) during a pregnancy. ...

If there is inadequate stimulation of the lining, due to lack of hormones, the endometrium remains thin and inactive. In humans, this will result in amenorrhea. After menopause, the lining is often described as being atrophic. In contrast, endometrium that is chronically exposed to estrogens, but not to progesterone, may become hyperplastic. Amenorrhoea (BE) or amenorrhea (AmE) is the absence of a menstrual period in a woman of reproductive age. ... Menopause is the physiological cessation of menstrual cycles associated with advancing age in women. ...

In humans, the cycle of building and shedding the endometrial lining lasts an average of 28 days. The endometrium develops at different rates in different mammals. Its formation is sometimes affected by seasons, climate, stress and other factors. The endometrium itself produces certain hormones at different points along the cycle. This affects other portions of the reproductive system. Norepinephrine A hormone (from Greek όρμή - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... The reproductive system is the ensembles and interactions of organs and/or substances within an organism that strictly pertain to reproduction. ...

Histology

The endometrium consists of a single layer of columnar epithelium, resting on a layer of connective tissue which varies in thickness according to hormonal influences - the stroma. Simple tubular uterine glands reach from the endometrial surface through to the base of the stroma, which also carries a rich blood supply of spiral arteries. In a woman of reproductive age, two layers of endometrium can be distinguished. These two layers occur only in endometrium lining the cavity of the uterus, not in the lining of the Fallopian tubes:^[1] In zootomy, epithelium is a tissue composed of a layer of cells. ... Connective tissue is one of the four types of tissue in traditional classifications (the others being epithelial, muscle, and nervous tissue. ... Hormone is also the NATO reporting name for the Soviet/Russian Kamov Ka-25 military helicopter. ... A gland is an organ in an animals body that synthesizes a substance for release such as hormones, often into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). ... The helicine branches of uterine artery (or helicine arterioles, or spiral arteries) are small arteries which temporarily supply the myometrium of the uterus during the luteal phase of the menstrual cycle. ...

• The functional layer is adjacent to the uterine cavity. This layer is built up after the end of menstruation during the first part of the previous menstrual cycle. Proliferation is induced by progesterone (follicular phase of menstrual cycle), and later increased by the progestrone from the corpus luteum (luteal phase). It is adapted to provide an optimum environment for the implantation and growth of the embryo. This layer is completely shed during menstruation.
• The basal layer, adjacent to the myometrium and below the functional layer, is not shed at any time during the menstrual cycle, and from it the functional layer develops.

In the absence of progesterone, the arteries supplying blood to the functional layer constrict, so that cells in that layer become ischaemic and die, leading to menstruation. Menstrual cycle The menstrual cycle is a recurring cycle of physiological changes in the females of some animal species that is associated with reproductive fertility. ... Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. ... The corpus luteum (Latin for yellow body) is a small, temporary endocrine structure in animals. ... It has been suggested that embryology be merged into this article or section. ... Menstrual cycle. ... The myometrium is the middle layer of the uterine wall consisting of smooth muscle cells and supporting stromal and vascular tissue. ... In medicine, ischemia (Greek ισχαιμία, isch- is restriction, hema or haema is blood) is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. ... Menstrual cycle. ...

It is possible to identify the phase of the menstrual cycle by observing histological differences at each phase:

This page is a candidate for speedy deletion. ... Menstrual cycle The luteal phase (or secretory phase) is the latter phase of the estrous cycle in animals, and the menstrual cycle in humans and great apes. ... The helicine branches of uterine artery (or helicine arterioles, or spiral arteries) are small arteries which temporarily supply the myometrium of the uterus during the luteal phase of the menstrual cycle. ...

Pathological conditions

Adenomyosis is the growth of the endometrium into the muscle layer of the uterus (the myometrium). Adenomyosis is a medical condition characterized by the presence of ectopic endometrial tissue (the inner lining of the uterus) within the myometrium (the thick, muscular layer of the uterus). ... The myometrium is the middle layer of the uterine wall consisting of smooth muscle cells and supporting stromal and vascular tissue. ...

Endometriosis is the growth of endometrial tissue outside the uterus.

Endometrial cancer is the most common cancer of the human female genital tract. Endometrial cancer involves cancerous growth of the endometrium (lining of the uterus). ... Cancer is a class of diseases or disorders characterized by uncontrolled division of cells and the ability of these cells to spread, either by direct growth into adjacent tissue through invasion, or by implantation into distant sites by metastasis (where cancer cells are transported through the bloodstream or lymphatic system). ...

See also

• Menstrual cycle
• Estrous cycle

Menstrual cycle The menstrual cycle is a recurring cycle of physiological changes in the females of some animal species that is associated with reproductive fertility. ... The estrous cycle (also oestrous cycle; originally derived from Latin oestrus) refers to the recurring physiologic changes that are induced by reproductive hormones in most mammalian placental females. ...

Additional images

Vertical section of mucous membrane of human uterus. Image File history File links No higher resolution available. ...

Histopathologic representation of endometrioid adenocarcinoma demonstrated in endometrial biopsy. Hematoxylin-eosin stain. Image File history File linksMetadata Download high resolution version (2040x1536, 1161 KB) Summary Histopathologic representation of endometrioid adenocarcinoma demonstrated in endometrial biopsy. ...

Blastocyst with an inner cell mass and trophoblast. Blastocyst. ...

microscopic slide of the endometrium. Image File history File linksMetadata Size of this preview: 800 × 600 pixel Image in higher resolution (2816 × 2112 pixel, file size: 2. ...

References

1. ^ Blue Histology - Female Reproductive System. School of Anatomy and Human Biology - The University of Western Australia http://www.lab.anhb.uwa.edu.au/mb140/CorePages/FemaleRepro/FemaleRepro.htm Accessed 20061228 20:35

External links

• SUNY Figs 43:05-15 - "The uterus, uterine tubes and ovary with associated structures."
• Histology at BU 18902loa - "Female Reproductive System uterus, endometrium"
• Swiss embryology (from UL, UB, and UF) gnidation/role02
• Histology at OU 20_01
• Histology at utah.edu. Slide is proliferative phase - click forward to see secretory phase