File:Bailey031.jpg

Fig. 31. Median sagittal sections showing successive stages of gastrulation in the frog's egg

Bracket, from Kellicott.

A, beginning of gastrulation

B, slight advance in invagination and beginning of epiboly

C, invagination and epiboly progressing, inflection of cells (involution) occurring around dorsal lip of blastopore which is now an obvious structure

D, epiboly has resulted in covering of a large part of yolk by lip of blastopore

E, blastopore is now circular and filled with the yolk plug (cf. Fig. 30, A, 4) and the archenteron appears as a small space

F, the blastoccel is nearly obliterated

G, gastrulation completed.

a, Archenteron; b, blastopore; c, rudiment of notocord; ec, ectoderm; en, entoderm; gc, gastrular cleavage, ge, entoderm (protentoderm) ; m, peristomal mesoderm; np, neural plate; w/, transverse neural ridge; s, blastocoel.

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Reference

Bailey FR. and Miller AM. Text-Book of Embryology (1921) New York: William Wood and Co.

Cite this page: Hill, M.A. (2024, April 23) Embryology Bailey031.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Bailey031.jpg

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