|
The body-stalk, also known as the allantoic stalk, is a band of mesoderm that connects the caudal end of the embryo to the chorion in development. With the formation of the caudal fold, the body-stalk assumes a ventral position; a diverticulum of the yolk-sac extends into the tail fold and is termed the hind-gut. With continued development, the body-stalk is later replaced by the umbilical cord. Body stalk anomaly occurs in approximately 1 in 15,000 births. It is a result of defects in the formation of cephalic, caudal, and lateral embryonic body folds. ==Additional images== File:Gray17.png|Human embryo—length, 2 mm. Dorsal view, with the amnion laid open. X 30. File:Gray22.png|Human embryo of 2.6 mm. File:Gray26.png|Diagram showing later stage of allantoic development with commencing constriction of the yolk-sac. File:Gray31.png|Model of human embryo 1.3 mm. long. File:Gray32.png|Section through ovum imbedded in the uterine decidua. File:Gray40.png|Embryo between eighteen and twenty-one days. File:Gray977.png|Human embryo about fifteen days old. Brain and heart represented from right side. Digestive tube and yolk sac in median section. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Body-stalk」の詳細全文を読む スポンサード リンク
|