EMBRYOLOGY OF TADPOLE AND CHICK 



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thin entoderm is separated from the middle layer. This separation of 

 layers is the delamination process we have been discussing. 



As the outer animal cells are pigmented, we assume that whenever 

 pigment is found in any of the inner cells, it is an indication that such 

 pigmented cells are derived from the ectoderm. 



As the yolk-plug is withdrawn, the blastopore becomes a mere slit, 

 while the ectoderm and mesoderm separate considerably, and dip down- 

 ward toward the entoderm in the dorsal midline, although never so far 



