DECIDUA [membrana decidua (LNH), s. caduca, s. decidua, s. decidua graviditatis; synonym deciduous cover] — the mucous membrane of a uterus which is exposed to certain transformations at pregnancy and disappearing after the delivery (it is allocated from a cavity of the uterus together with lokhiya). In D. islands distinguish three departments: 1) basal D. of the lake [decidua basalis (LNH), s. decidua serotina] — the part of a mucous membrane located between a bag of waters and a muscular coat of a uterus; 2) capsular D. of the lake [decidua Capsularis (LNH), s. reflexa] — the part of a mucous membrane separating a bag of waters from a cavity of the uterus; 3) parietal D. of the lake [decidua parietalis (LNH), s. decidua vera] — all other part of a mucous membrane uterus (see).
At the beginning of D.'s pregnancy by the lake represents thickened (to 1 cm) a mucous membrane with strongly expanded glands and the large decidual cells (cellulae deciduales) containing a glycogen. A number of authors considers that the nutrients (glycogen) which are contained in decidual cells serve for food of egg at an early stage of its development in a uterus.
The parietal decidua since VI month of pregnancy is squeezed by the growing fruit and is exposed to involution, the epithelium on its surface and in glands disappears (except their deepest departments). The Ampuloobrazny ends of glands, being squeezed, form cracks.
The capsular decidua stretched by a bag of waters begins to atrophy since the end of the II month of pregnancy, in the next months pregnancies the lake nestles the growing fruit on parietal D. and atrophies.
The basal decidua participates in education maternal, or uterine, parts placentae (see). The basal D.'s layers of the lake turned to a fruit (compact and spongy), are exposed to destruction of a vorsinama of chorion, and on their place the lacunas filled with blood are formed. Its deep layers form a basal plate, from a cut the dividing spaces filled with blood on separate cameras depart to chorion of a partition. The fringe region of basal D. of the lake forms the closing plate of a placenta. From V month of pregnancy in it the colossal multi-core cells of a trophoblastic origin specific to a placenta appear. Decidual cells in a mucous membrane of a uterus appear also at the end of the second half of a menstrual cycle — the so-called menstrual D. of the lake (decidua menstrualis) disappearing in the period of periods. Decidual cells develop not only at a uterine pregnancy, but also at a row patol, conditions of the female sexual device, and also an extrauterine pregnancy that can be one of its diagnostic characters (see. Extrauterine pregnancy ).
E. A. Vorobyova.