168 



Foregut 



THE GERM LAYER DERIVATIVES 



Neurocoel 



Rhombocoel 



Mesocoel 



Dorsal thickening 



,Tuberculum posterius 

 Prosocoel 

 Epiphysis 

 infundibulum 

 Diocoel "l 



Prosocoel 

 Telocoel J 



Torus tronsversus 



Optic recess 

 Optic chiasma 



Epithelial hypophysis 



Oral plate (stomodeal invagination) 

 Heart mesoderm 



Liver diverticulum 



Oesophageal plug Cerebellum 

 IMotochord \ Rhombocoel / lyiesence 



m posterius ' 



physis 

 locoel 

 Telencepholon 



Telocoel 



Torus tronsversus 



Optic recess 

 Hypophysis 



Gall bladder 



Lung 



Ventricle 



Development of the brain and anterior structures of the frog tadpole. (Top) 

 Median sagittal section of the 7 mm. frog tadpole. {Bottom) Median sagittal 

 section of the 1 1 mm. frog tadpole. 



