[Structural organization of human yolk sac epithelium during first three months of intrauterine development].
Epithelium of the endodermal origin in the human yolk sac was studied at prenatal weeks 5-12. In the beginning of the period studied the epithelium was characterized by high volume density, distribution in the different zones of the organ and polymorphism. The highest secretory activity of epitheliocytes was observed at weeks 7-8 of intrauterine development. After this period, epithelium total volume density decreased, while the fraction of inner epithelial lining layer increased. The epithelium-lined cavities in the yolk sac wall shrinked and disappeared, and the volumes of the cells and nuclei decreased. These morphological changes of the epithelium are indicative of the loss of the organ basic functions already by the end of embryonic period of human development.
Dubinina
N N
NN
Novikov
V D
VD
Sklianov
Iu I
IuI
Bychkova
N A
NA
Dubinin
E V
EV
D047108:Embryonic Development; D004847:Epithelial Cells / Q000166:cytology; D004848:Epithelium / Q000196:embryology / Q000502:physiology; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D015017:Yolk Sac / Q000166:cytology*