A treatise on the science and practice of midwifery . placentalend of the umbilical cord at the full period of preg-nancy. The umbilical vesicle is filled with a yel-lowish fluid, containing many oil- and fat-globules,similar to the yelk of an egg. The Allantois.—Somewhere about the twentiethday after conception a small vesicle is formed towardthe caudal extremity of the foetus, which is calledthe allantyis. This membrane in mammals is im-portant, as it forms the greater part of the fetalplacenta, a small portion of it remaining inside thebody permanently as the bladder. It begins as adivertic
A treatise on the science and practice of midwifery . placentalend of the umbilical cord at the full period of preg-nancy. The umbilical vesicle is filled with a yel-lowish fluid, containing many oil- and fat-globules,similar to the yelk of an egg. The Allantois.—Somewhere about the twentiethday after conception a small vesicle is formed towardthe caudal extremity of the foetus, which is calledthe allantyis. This membrane in mammals is im-portant, as it forms the greater part of the fetalplacenta, a small portion of it remaining inside thebody permanently as the bladder. It begins as adiverticulum from the lower part of the intestinalcanal. This, at first spherical, rapidly develops andbecomes pyriform in shape, while, by a process ofconstriction similar to that which occurs in the vitel-lus to form the umbilical vesicle, it becomes divided into two partsmunicating with each other, the smaller of them being eventuallydeveloped into the urinary bladder. The larger portion, leaving (heabdominal cavity along with the vitelline duct, rapid. An Embryo of abouttwenty-live days laid open. i After Coste.)a. Chorion. /•. ;•. Cavity of ;l. Umbilical ;?. Pedicle of Embryo. coin- grows until il 108 PREGNANCY. comes into contact with the most external ovular membrane, the chorion,over the entire inner surface of which it spreads. In this part vesselssoon develop—namely, the two umbilical arteries, derived from theabdominal aorta, and two umbilical veins, one of which subsequentlydisappears; these, along with the vitelline duct and the pedicle of theallantois, form the umbilical cord. The main and very important func-tion of the allantois, therefore, is to carry the foetal vessels up to theinner surface of the subzonal membrane. Besides this purpose, the allan-tois, at a very early period, may receive the excretions of the foetus and Fig. 58.
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectobstetrics, bookyear1
