Decidua 3258771 214891909 2008-05-25T19:47:58Z Thijs!bot 1392310 robot Adding: [[pt:Decídua (animal)]] {{Infobox Anatomy | Name = {{PAGENAME}} | Latin = | GraySubject = 12 | GrayPage = 59 | Image = Gray33.png | Caption = Diagrammatic sections of the uterine mucous membrane: A. The non-pregnant uterus. B. The pregnant uterus. | Image2 = Gray34.png | Caption2 = Sectional plan of the gravid uterus in the third and fourth month. | System = | MeshName = Decidua | MeshNumber = A16.759.289 | }} '''Decidua''' is the term for the [[uterus|uterine]] lining ([[endometrium]]) during a [[pregnancy]], which forms the maternal part of the placenta. It is formed under the influence of [[progesterone]] and forms highly-characteristic cells. ==Etymology== The word comes from the [[Latin]] ''deciduus'', meaning ''falling off or shedding''. ==Background== After [[ovulation]], in [[mammal]]s, the endometrial lining becomes transformed into a secretory lining in preparation of accepting the [[embryo]]. Without [[implantation]], the secretory lining will be absorbed ([[estrous cycle]]) or shed ([[menstrual cycle]]). With implantation the lining now termed ''decidua'' evolves further during the pregnancy. The decidua is shed during the [[parturition]] process. ==Structure== Different layers of the deciduas have been described: * a compact outer layer (''stratum compactum'') * an intermediate layer (''stratum spongiosum'') * a boundary layer adjacent to the [[myometrium]]. That part of the decidua that interacts with the trophoblast is the ''decidua vera'' (“true decidua”). The remainder of the decidua is termed the ''decidua parietalis''. The decidua has a [[histology|histologically]]-distinct appearance, displaying large polygonal decidual cells in the stroma. These are enlarged endometrial stromal cells, which resemble [[epithelium]] (and are referred to as "epithelioid"). Formation of a specialized decidua is called [[decidualization]], which is a special property of endometrium seen only in [[hemochorial placentation]]. Decidualization includes the process of differentiation of the spindle-shape stromal fibroblasts into the plump secretory decidual cells, which create a pericellular extracellular matrix rich in fibronectin and laminin (similar to epithelial cells). Vascularity, as well as vascular permeability, is enhanced in the decidualizing endometrium. Its [[leukocyte]] population is distinct, with the presence of large endometrial granular leukocytes being predominant, while polynuclear leukocytes and B-cells are scant. The large granular lymphocytes (CD56 bright) are called "uterine [[NK cells]]" or "uNK cells" in mice, and "decidual NK cells" or "dNK cells" in humans. The border to the [[trophoblast]] is called Nitabuch’s layer''. ==Role== As the maternal interface to the embryo the decidua participates in the exchanges of nutrition, gas, and waste with the gestation. It also protects the pregnancy from the maternal [[immune system]]. Further, the decidua has to allow a very controlled invasion of the trophoblast. In invasive placental disorders like [[placenta accreta]] decidualization have been consistently found to be deficient. ==Hormone production== The decidua secretes [[hormones]], [[growth factor]]s, and [[cytokine]]s. It has receptors for [[estrogen]], [[progesterone]], [[growth hormone]], and others. Among its products are hormones commonly associated with other organs such as [[cortisol]], [[CRF]], [[GnRH]], [[prolactin]], and [[relaxin]]. Decidual prolactin is not under [[dopamine]]rgic control. [[Pregnancy protein 14]] (PP-14), also called placental protein 12, and [[Insulin-like growth factor-binding protein 1]](IGFBP1) appear to be specific products of the secretory and decidual lining. Other factors released include [[interleukin]]-15 and [[vascular endothelial growth factor]] (VEGF). A reasonable understanding of the role and interplay of these hormones and factors has not been evolved. ==Other== *In case of an [[extrauterine pregnancy]], the endometrium nevertheless becomes decidualized. A woman may shed the lining in the form of a decidual cast, which may be mistaken as a [[miscarriage]], when, in fact, the ectopic still persists. *A decidual reaction can be observed in tissue of the [[peritoneum]] and [[ovary]] during a pregnancy, and represents a response of stromal tissue to progesterone. ==Additional images== <gallery> Image:Gray39.png|Scheme of placental circulation. </gallery> ==See also== *[[decidualization]] ==External links== * [http://www-medlib.med.utah.edu/WebPath/PLACHTML/PLAC094.html Histologic picture at med.utah.edu] * {{GraySubject|12}} * {{BUHistology|19904loa}} {{Embryology}} [[Category:Female reproductive system]] [[Category:Obstetrics]] [[es:Decidua]] [[it:Decidua basale]] [[pt:Decídua (animal)]]