The practice of obstetrics, designed for the use of students and practitioners of medicine . illi over the layer of Langhans. 70 PHYSIOLOGICAL PREGNANCY. that it is a fetal structure; and the chorionic villi, although bathed in maternalblood, separate the latter from the embryonic blood. The vilH assume differentcharacteristics at different stages of development. At the stage of formation ofthe placenta at the third month they are irregular, short, and thickset (Fig. 97).Later they are more regular and the angle formed by the junction of theirbranches with the parent stem is more obtuse (Fig.
The practice of obstetrics, designed for the use of students and practitioners of medicine . illi over the layer of Langhans. 70 PHYSIOLOGICAL PREGNANCY. that it is a fetal structure; and the chorionic villi, although bathed in maternalblood, separate the latter from the embryonic blood. The vilH assume differentcharacteristics at different stages of development. At the stage of formation ofthe placenta at the third month they are irregular, short, and thickset (Fig. 97).Later they are more regular and the angle formed by the junction of theirbranches with the parent stem is more obtuse (Fig. 98). At the close of preg-nancy their arrangement is more regular, while the branches are less denselycrowded and far more slender (Fig. 99). Knowledge of the appearance ofthe villi is most important, since the existence of pregnancy is positively con-firmed by their microscopic detection in suspicious discharges from the embedding of the villi in the decidua is never very intimate, and through-out their course of development they can be extricated with very little Fig. ioi.—Ovum of Fig. 100 Cut Open, showing Embryo and Amnion. X 2J.— {Authors case.) A large number of the villi do not penetrate the decidua to any depth; thosewhich are intimately joined to it are called the anchoring or fastening villi. The Placenta.—The placenta is the essential nutritive and respiratory organof the fetus. It results from the union of the chorion frondosum, q. v. (placentafoetalis), and the decidua serotina (placenta matemalis). Formation: In addi-tion to the growth of the chorionic villi, q. v., there are extensive changes inthe placental region of the decidua, which also proliferates and forms septa;these, growing down between the chorionic villi, sometimes reach the surfaceof the chorion. It is only at the margins of the placenta that the decidual septaare well marked. Interesting and important formations in the placenta arethe intervillous spaces. The decidua v
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectobstetrics, bookyear1
