152 MICROSCOPIC ANATOMY OF THE ORGANS. 



faces of the cells. In the medulla the network of nerves is 

 much richer. A part of the branches from this end in the 

 vessel walls, while the greater number surround the gland cells 

 and form fine plexuses around them. 



7. HYPOPHYSIS CEREBRI (PITUITARY BODY). 



The pituitary body in adult animals consists of two lobes, a 

 posterior and an anterior. The posterior lobe is made up mainly 

 of neuroglia elements. There are, however, in this region other 

 cells which are considered by some to be nerve cells. Their 

 nature is uncertain. The anterior lobe consists, on the con- 

 trary, of solid glandular masses separated by connective-tissue 

 septa and capillary networks (Fig. 109). This glandular tissue 



FIG. 109. 



Endothelium of 

 vessel wall 



Blood-vessek 





Gland walls'^ & 



Ji'saj" .'* *.:, 



From a section of the hypophysis cerebri of a dog. X 300. 



consists of epithelial cells, concerning whose glandular nature 

 there can be no doubt. They are round or polyhedral, and, 

 according to some authors, are of two types. One kind of cell 

 is of dark appearance, large and granular, and has a marked 

 affinity for staining fluids. These are called chromophile cells. 

 The other kind is small and clear. The two types are about 

 equally distributed. Other authors regard the differences in 

 appearance between the two kinds of cells to be due to post- 

 mortem or functional changes. 



In the posterior part of the anterior lobe there are found 



