Blastula 



■%i'.as-S-' 



Primitive 

 streak 



Primitive y^x'^h^': /^. 

 groove ^ K'^.-'f''- 



ginning of gut Notochord 



D. Longitudino! section E. Cross section 



Fig. 30. Gastrulation in the chick. 



Endoderm 



Ventral 

 sctoderr 



Blastula 



Gastrula 



Ectoderm - 



Epidermis and Brain and 



associated structures nervous system 

 ( hair, nails, etc. ) 



Mesoderm 



Notochord - 



• Endoderm 

 Embryonic gut 



Inner lining of 

 digestive tract 



Inner lining of 

 respiratory tract 



Glands — including 

 liver, pancreas 



Somites 



Muscle 



Outer covering 

 of internal 



organs 



Mesenchyme 

 (loose, migratory cells) 



Dermis (inner 

 skin layer ) 



Excretory 

 system 



Bones and cartilage 



Circulatory system — 



including heart, blood vessels, etc. 



61 



