A System of midwifery : including the diseases of pregnancy and the puerperal state . he formation, by a process of involution, ofthe amnion, an important structure, the further development of whichwill be traced presently. The blastodermic vesicle,then, is surroundedby the zona pellucida Z. It i< itself composed of two layers, the ex-ternal or serous ( %), which is continuous with the external surface ofthe embryo, and from which the amnion is developed ; and the internalor niumib < /// ). which subsequently subdivides as we have seen. If welook, however, at the mucous layer, in its ori
A System of midwifery : including the diseases of pregnancy and the puerperal state . he formation, by a process of involution, ofthe amnion, an important structure, the further development of whichwill be traced presently. The blastodermic vesicle,then, is surroundedby the zona pellucida Z. It i< itself composed of two layers, the ex-ternal or serous ( %), which is continuous with the external surface ofthe embryo, and from which the amnion is developed ; and the internalor niumib < /// ). which subsequently subdivides as we have seen. If welook, however, at the mucous layer, in its original and simplest form,we may assume that the umbilical vesicle and the intestinal surface of VI.] THE AMNION AND CHORION. 105 the embryo are indentical and continuous, both being derived from thesame layer. In Fig. 55, the same parts are shown in a more advanced stage ofdevelopment. The embryonic portion of the blastodermic vesicle ismore denned, and of larger size, and the umbilical vesicle is diminishedin a corresponding degree, while the communication between the two Fig. a. a Diagram showing early stage ofdevelopment.
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectobstetrics, bookyear1
