15° 



THE DISSECTION OF PIG EMBRYOS FOR STUDY 



diaiccplialoii appears the anlage of the epiphysis or pineal gland, and the chorioid 

 plexus of the third ventricle. This extends into the lateral ventricles as the 

 lateral chorioid plexus. The dorsodateral wall of the diencephalon thickens to 



Isthmus Mesencephalon 



Meten 



Chorioid plexus four 

 Hypoph 



Tela chorioidea fourth ventricle 

 Myelenecphalon 



Epiglottis _^ 



Common bile duct 



Duodenum 



Genital ridge 



Mctanephr'os 



I 

 Mcsoncphric duct 



cnilal sinus 



Ureter 



Fig. 141. — Median sagittal dissection of an iS mm. pig embryo, showing central nervous system in 



section and the viscera in position. 



form the thalamus and the third ventricle is narrowed to a vertical slit. The 

 increased size of the cerebellum has been noted. Into the thin dorsal wall of the 

 myelencephalon grows the network of vessels which form the chorioid plexus of 



