The development of the human body; a manual of human embryology . , elsewhere it becomes more or less flattenedand shows a tendency toward degeneration. In addition to these changes, the epithelium of themucosa disappears completely during the first month ofpregnancy, and the tissue between the glands in the stra-tum compactum becomes packed with large, often multi-nucleated cells, which are termed the decidual cells. After the end of the fifth month the increasing size ofthe embryo and its membranes exerts a certain amount ofpressure on the decidua, and it begins to diminish in thick-ness. Th
The development of the human body; a manual of human embryology . , elsewhere it becomes more or less flattenedand shows a tendency toward degeneration. In addition to these changes, the epithelium of themucosa disappears completely during the first month ofpregnancy, and the tissue between the glands in the stra-tum compactum becomes packed with large, often multi-nucleated cells, which are termed the decidual cells. After the end of the fifth month the increasing size ofthe embryo and its membranes exerts a certain amount ofpressure on the decidua, and it begins to diminish in thick-ness. The portions of the glands which lie in the stratumcompactum become more and more compressed and 152 THE DEVELOPMENT OF THE HUMAN BODY. finally disappear, while in the spongiosum the spaces be-come much flattened and the vascularity of the wholedecidua, at first so pronounced, diminishes greatly. (b) Decidua reflexa.—The decidua reflexa receives itsname from the fact that it was supposed to arise as a foldof the mucous membrane of the uterus and to be reflected. Fig. 74.—Section op an Ovum of 1 mm. A Section of the Embryo Lies in the Lower Part of the Cavity of the , Decidua; , uterine epithelium; Sch, blood-clot closing the aperture left by the sinking of the ovum into the uterine mucosa. •—(From Strahl, after Peters.) over the ovum after this had attached itself. Recentobservations, however, throw doubt on this mode of , the ovum described by Peters (Fig. 74) was alreadyalmost completely enclosed by the reflexa, a small areaat one pole being alone exposed. The uterine epithe- THE DECIDILE. I 53 Hum around the margins of this unenclosed area wasexceedingly thin and had the appearance of beingstretched by the growth of the ovum. Peters interpretsthe condition found in this very early stage by supposingthat when the ovum reached the uterus it came into con-tact with the thickened mucosa at a point where theepithelium had been thrown off and at once pro
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
