ObstetricsA manual for students and practitioners . a,a, projecting folds of amnion; z, zonapellucida; s, epiblast; »i, hypoblast; w,umbiliCHl vesicle. a,a, folds of amnion about to join; p,commencement of allantois. abdominal cavity of the foetus through a constricted portion called thevitelline duct, and containing a yellowish, oily fluid from which thefoetus derives its nourishment during the first few weeks of Fig. 8. life. It attains its greatestdevelopment by the end ofthe fourth week. From thistime on it gradually shrinksuntil by the sixth or seventhweek it has entirely disap-peared. It
ObstetricsA manual for students and practitioners . a,a, projecting folds of amnion; z, zonapellucida; s, epiblast; »i, hypoblast; w,umbiliCHl vesicle. a,a, folds of amnion about to join; p,commencement of allantois. abdominal cavity of the foetus through a constricted portion called thevitelline duct, and containing a yellowish, oily fluid from which thefoetus derives its nourishment during the first few weeks of Fig. 8. life. It attains its greatestdevelopment by the end ofthe fourth week. From thistime on it gradually shrinksuntil by the sixth or seventhweek it has entirely disap-peared. It is formed fromthe internal layer of the blas-todermic membrane. What is the allantois? It is a small vesicle derivedfrom the entoderm and innerstratum of the mesoderm,formed about the twentiethday near the caudal extrem-ity of the foetus, and Ijnngbetween the amnion and cho-rion. It is connected withthe bladder by the urachus,and grows rapidly until it en-tirely lines the chorion. This contains the two umbilical arteries derived from the aorta,
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectobstetrics, bookyear1
