From Big Medical Encyclopedia

PLACENTAL PLATFORM (Latin placenta, from grech, plakus flat cake) — the place of an implantation of placenta to a wall of a uterus.

At normally proceeding pregnancy of Pct is located in an upper segment of a uterus, on a front or back wall of her cavity, is more rare at a bottom or in the field of pipe corners of a uterus. The arrangement of Pct in the lower segment of a uterus, especially near an internal pharynx is pathological (see. Placental presentation ). The sizes of Pct, as a rule, correspond to size placentae (see); diameter of Pct is 17 — 20 cm, a form its usually roundish. Directly after the delivery and departments of a placenta diameter of Pct is cut by half, by the beginning of the second week of a puerperal period of Pct decreases in the diameter approximately to 4,5 cm, in the subsequent reduction of Pct happens according to puerperal involution of a uterus.

Normal during pregnancy and childbirth of Pct it is reduced in much smaller degree, than all other parts of a uterus. Thanks to this feature of sokratitelny activity of a uterus of peeling of a placenta during pregnancy, and also during the first and second periods of childbirth normal does not occur.

In the course of puerperal placental detachment the integrity of the uteroplacental vessels which are especially developed in the field of Pct is broken. Gleams of these vessels contract at reductions of muscles of a uterus, in vessels of Pct blood clots are formed that promotes a stop of bleeding; in the subsequent a part of vessels in the field of Pct is obliterated.

Process of healing of Pct begins in the first days of a puerperal period and comes to the end approximately by the end of the second month. At first there is a disintegration and rejection of scraps of a spongy layer decidua (see), clots, blood clots that is promoted by the enzymes and other biologically active agents which in particular are formed as a result of a leucolysis. The breaking-up particles of a decidua, clots and other fabric elements are torn away and are a part of lokhiya. At the same time ground particles of glands and a stroma of a basal layer of a mucous membrane of a uterus are bared. In the course of regeneration there is a growth of glands, proliferation of stromal cells of a basal layer of a mucous membrane, recovery of vascular network and nerve terminations of an endometria, epithelization of the area which was Pct. Complete regeneration in the field of Pct happens after regeneration of the endometria which is located outside Pct and comes approximately in 2 months.

Bibliography: Vartapetova V. G. To a question of influence of size of a placenta on the course of childbirth and a puerperal period, Owls. medical, No. 3, page 85, 1960; Anderson W. Davis I. Placental site involution, Amer. J. Obstet. Gynec., v. 102, p. 23, 1968; Klinik der Frauenheilkimde und Gebu-rtshilfe, hrsg. v. G. Doderlein u. K. - H. Wulf, Bd 2, S. 338, Miinchen u. a., 1975.

V. I. Bodyazhina.