Histological Appearances of the Mammalian Pituitary Body 131 



into the nervous substance, and strands of it may pass quite deeply into 

 it, and even into the brain tissue in the neighbourhood of the floor of the 

 third ventricle. The cleft is here again a closed cavity, and is not nearly 

 so well developed as in the pituitaries of the cat and dog. In some cases 

 very little of it remains, but the epithelium which lies between it and the 

 nervous substance of the posterior lobe is always distinct from that of the 

 main mass of the anterior lobe and contains no eosinophil cells. The same 



Fio. 5.— Mesial sagittal section through the ])ituitary body of au adult 

 monkey. (Semi-diagrammatic. ) 

 «, optic chiasma; 6, tongue-like process of pars intermedia; c, tliird ventricle; rf, anterior lobe proper; 

 e, epithelial cleft: g, nervous substance of posterior lobe; i", epithelial investment of posterior lobe; 

 k, epithelium of pars intermedia extending over and intu adjacent brain substance. 

 The dark shading indicates the anterior lobe proper; the lighter shading shows the position of the epithelium 

 of the pars intermedia. 



is true of the epithelium which invests the neck and sides of the posterior 

 lobe. In this respect the epithelial investment of the nervous portion 

 resembles that of the pituitaries of the cat and dog, and like them, too. 

 may contain colloid-holding vesicles, but they are comparatively scarce in 

 the monkey, and are not always present. 



In the pituitary body of the monkey there is, tiien, a very complete 

 fusion of the tissues derived from the buccal mucous membrane and from 



