A textbook of obstetrics . e of the placenta contrastsstrongly with the maternal surface. The latter is of a dark-redhue, divided by deep sulci into lobules of irregular outline and i [8 PREGNANCY extent,—the cotyledons. Over the maternal surface of the pla-centa is stretched a delicate, -ravish, transparent membrane,which is made up n( the cells that compose the upper layer of thedecidua serotina. This constitutes the maternal portion of theplacenta. In separating from the uterine wall, therefore, the lineof separation docs not divide the fetal from the maternal struc-tures, hut is Ununl in t
A textbook of obstetrics . e of the placenta contrastsstrongly with the maternal surface. The latter is of a dark-redhue, divided by deep sulci into lobules of irregular outline and i [8 PREGNANCY extent,—the cotyledons. Over the maternal surface of the pla-centa is stretched a delicate, -ravish, transparent membrane,which is made up n( the cells that compose the upper layer of thedecidua serotina. This constitutes the maternal portion of theplacenta. In separating from the uterine wall, therefore, the lineof separation docs not divide the fetal from the maternal struc-tures, hut is Ununl in the mucous membrane of the uterus, in thelower <A the cellular layer of the decidua. Around theperiphery of die placenta may be seen a large vein, the circularvein of the placenta, which returns a part of the maternal bloodfrom the organ, the remainder returning to the maternal circula-tion by means of the continuity between the placental lacunaeand the uterine sinuses. The situation of the placenta within the. Fig. 90.—Diagram of uterus and placenta in the fifth month: Ch Chorion-am, amnion; / , /; villi; /., /., lacuna; s, serotina; v, small arteries; .. glandu-lar layer; m, uterine muscle (Leopold). uterus may with equal frequency be found either upon the poste-rior or the anterior wall ; occasionally, however, upon one of thelateral walls, more frequently the right (Schroeder). A perpendicular section through the middle of a placenta that is still attached to the uterine wall reveals an intimateconnection between tin- two. The delicate terminal villi, andeven branches a millimeter in thickness, are imbedded in theupper portion of the decidua, and held in place by theirextremities bulging out into club-shaped masses, so that theexercise of considerable force will not extract them from the uterine mucous membrane, but will, instead, always lacerate the maternal structures. I h< functions of the placenta are manifold. Not onlydoes it THE PLACENTA. I 19 act as
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Keywords: ., bookcentury1800, bookdecade1890, bookidtex, booksubjectobstetrics
