A treatise on the science and practice of midwifery . An Embryo of about twen-ty-five days laid open.(After Coste.)a. Chorion, b. Cavity of chorion, vesicle, e. Pedi-cle of allantois. /. Em-bryo. CONCEPTION AND GENERATION, 97 the umbilical vesicle, it becomes divided into two parts, communi-cating with each other, the smaller of them being eventually de-veloped into the urinary bladder. The larger portion, leaving theabdominal cavity along with the vitelline duct, rapidly grows untilit comes into contact with the most external ovular membrane, thechorion, over the entire
A treatise on the science and practice of midwifery . An Embryo of about twen-ty-five days laid open.(After Coste.)a. Chorion, b. Cavity of chorion, vesicle, e. Pedi-cle of allantois. /. Em-bryo. CONCEPTION AND GENERATION, 97 the umbilical vesicle, it becomes divided into two parts, communi-cating with each other, the smaller of them being eventually de-veloped into the urinary bladder. The larger portion, leaving theabdominal cavity along with the vitelline duct, rapidly grows untilit comes into contact with the most external ovular membrane, thechorion, over the entire inner surface of which it spreads. In thispart vessels soon develop: namely, the two umbilical arteries, de-rived from the abdominal aorta, and two umbilical veins, one ofwhich subsequently disappears; these, along with the vitelline ductand the pedicle of the allantois, form the umbilical cord. The mainand very important function of the allantois, therefore, is to carrythe foetal vessels up to the inner surface of the sub-zonal membrane. Fig. I. Exo-chorion. 2. External layer of the blastodermic memlirane. 3. Umbilical vesicle. 5. Amnion. 6. Embryou. 7. Pedicle of Allantois. Besides this purpose, the allantois, at a very early period, may receivethe excretions of the foetus, and serve as an excrementitious to Cazeaux, scarcely a trace of the allantois can he seena few da}rs after its formation. Its lower part or pedicle, bowever,long remains distinct, and forms part of the umbilical cord; andtraces of it may be found even in adult life in the form of the urachus,which is really the dwindled pedicle, and forms one of the Ligamentsof tlie bladder. The Corps Reticule or Viiriform Body.—Between the chorion andamnion is often found a gelatinous fluid, with minute filamentousprocesses traversing It, called by Velpeau the corps reticul^ whichis not met with until the allantois comes into contad with the cho-rion, and which seems to he formed out of
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Keywords: ., bookcentury1800, bookdecade1870, bookidtre, booksubjectobstetrics
