THE SUPRARENALS 



237 



cells, and is differentiated into three layers, by the way in 

 which these cells are arranged. From without inwards 

 these layers are — 



1. Zona glomerulosa, in which the cells have an alveolar 

 formation. 



Fig. 34. — Suprarenal cells of medulla stained brown with potassium 

 bichromates. Note the blood sinuses continuous with those of 

 the zona reticularis (Schafer, The Endocrine Organs). 



2. Zona fasciculata, where they form single columns, 

 running radially. 



3. Zona reticularis, in which they form an open mesh- 

 work. 



The cortical cells contain a doubly refracting hpoid 

 composed of lecithin and cholesterol esters. In the inner- 

 most layer they contain a pigment. 



