Gynecology . e malformations are different grades of the same embryonic defect. In the early stages of development the cloacal membrane reaches to theprimitive belly-stalk or forerunner of the umbilical cord. As the embryo growsthe upper portion of this membrane disappears as the sides of the abdominalwall and pelvis join, while the lower part corresponds to the opening of the uro-genital sinus and the rectum. 388 GYNECOLOGY Under abnormal conditions the cloacal membrane may partially or entirelypersist, due to the incomplete merging in the middle line of the sides of themuscular abdominal wal
Gynecology . e malformations are different grades of the same embryonic defect. In the early stages of development the cloacal membrane reaches to theprimitive belly-stalk or forerunner of the umbilical cord. As the embryo growsthe upper portion of this membrane disappears as the sides of the abdominalwall and pelvis join, while the lower part corresponds to the opening of the uro-genital sinus and the rectum. 388 GYNECOLOGY Under abnormal conditions the cloacal membrane may partially or entirelypersist, due to the incomplete merging in the middle line of the sides of themuscular abdominal wall or of the pelvis. The thin epithelial cloacal membrane ^=: iTLatesTVne. 1 1 I B *? ^^Jjcx^tr CloaccxV m ^0 point o^ 3fcmWwg^r W Ua\oy\ ofbucks i^ Cloaca, Fig. 167.—Common cloaca into which thegut and the allantois empty. The cloacal mem-brane reaches to the region of the later bladderand urethra. Knowledge of this membrane isimportant in understanding exstrophy of thebladder (Pankow). Jesuit*- Got ^uUe^. Fig. 168.—The cloaca separates into a ven-tral and dorsal part. The Wolffian ducts openinto the ventral part. Mullers ducts at thisstage are not established. The dotted line showsthe position of their later development. Thebeginning of the bladder can be seen as a dilata-tion in the duct of the allantois (Pankow). thus exposed soon breaks and allows the urinary contents of the bladder toescape through the opening of the belly wall. If the opening is extensive the AUcmWiCv^
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