The practice of obstetrics, designed for the use of students and practitioners of medicine . he splanchnic layerof the mesoderm until contact is made with the chorion, thus forming alarge sac containing fluid. But in man the entodermic diverticulum is a mererudiment (Fig. 66) which can be traced along the umbilical cord for some distancebut does not form a free sac. A mesodermic layer, however, perfectly analogousto that of other mammals, does connect the caudal end of the embryo with thechorion and serves to carry the blood-vessels from the embryo to the chorionicvilli. This mesodermic layer,
The practice of obstetrics, designed for the use of students and practitioners of medicine . he splanchnic layerof the mesoderm until contact is made with the chorion, thus forming alarge sac containing fluid. But in man the entodermic diverticulum is a mererudiment (Fig. 66) which can be traced along the umbilical cord for some distancebut does not form a free sac. A mesodermic layer, however, perfectly analogousto that of other mammals, does connect the caudal end of the embryo with thechorion and serves to carry the blood-vessels from the embryo to the chorionicvilli. This mesodermic layer, as seen above, is precociously formed. As inother mammals, the proximal portion of the allantoic rudiment forms the urinarybladder and the urachus which becomes one of the ligaments of the latter. The Chorion.—There is probably no organ in the human fetus which hasbeen the subject of such false conceptions as the chorion. It is defined by Minotas follows: The whole of that portion of the extra-embryonic somatopleurewhich is not concerned in the formation of the amnion. As shown above,. Fig. 99.—Chorionic Villi at Full Term.—{Minot.) THE CHORION. 69 the young human ovum already has a chorion with a mesodermic lining (Figs. 64and 51). It is covered by villi, solid outgrowths of the epithelial layer, whichshow slight cavities at their bases into which the mesoderm protrudes. Thevilli extend into the uterine mucous membrane in such a way as to indicatethat epithelium, glands, and walls of blood-vessels in their path have been dis-integrated and not merely pushed aside; that is, they protrude freely into thematernal blood. In the somewhat later stage shown in Reicherts ovum () the villi are grouped in a band, leaving the two flattened poles of the ovumbare. Still later the villi become hollow with two distinct layers of epithelium,and soon are penetrated by blood-vessels which have entered the mesodermof the chorion. The simple club-shaped villi of the early ovum soon b
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectobstetrics, bookyear1
