The Development of tlie Mammalian Pituitaiy Body 



LSI 



cat the nervous tissue of tlie posterior lobe is almost entirely destroyed by 

 an overgrowth of epithelial cells of the pars intermedia. These observa- 

 tions and the occurrence of epithelial cells in the brain substance of the 

 floor of the third ventricle in the adult monkey seem to point to some 

 physiological connection between epithelial cells and cerebro-spinal canal. 



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Fig. 11. — j\lesial sagittal section through {jostero-supeiior angle of the 



posterior lobe of the pituitary of a third kitten near full time. 



Drawing from a photograph. 

 b, central cavity of posterior lol)e ; d, canal leading from this cavity into c, epithelial 



cells of pars intermedia ; /, cells of pars intermedia jind cleft lying below the 



posterior lobe. 



Since the intimate relations that exist between the two from the earliest 

 stages of development are not only maintained but emphasised in the adult 

 mammalian pituitary, it is unlikely that they are accidental, and Kupf f er's 

 hypothesis as to the signiflcance of the pituitar}' body appears to ha%e 

 many facts that support it. The nature of the connection between epithe- 

 lium and cerebro-spinal canal from a physiological point of view awaits an 



