THE ADRENAL (ELANDS 



261 



narrow zone, the zona glonierulosa, wliere the polyhedral-shaped 

 cells are arranged in oval groups in the form of flattened or 

 incomplete vesicles. The nuclei stain deeply and the cytoplasm 

 has an affinity for basic dyes. Internal to this is the zona fascicu- 

 lata, with long double rows of larger polyhedral or somewhat 

 cuboidal-shaped cells, often binucleate, radiating in toward the 

 medulla. In the outer portion of these colunms the cells have fat 

 droplets and cholesterol, but usually the technique dissolves the 



Z. reticularis 



Fig. 162. — Diagram of a section through the adrenal of a mammal. 



lipoid substance, so that the cells may have a spongy appearance. 

 Internal to the zona fasciculata is the narrow zona reticularis with 

 cells forming a meshwork of cords one cell in width. These cells 

 contain a brown pigment which increases toward the boundary of 

 this zone with the medulla and becomes more e\ident in glands of 

 old animals. A capillary net in\'ests the cell groups in the glonier- 

 ulosa, and from it capillaries extend between double rows of cells of 

 the fasciculata to become a meshwork again in the reticularis, where 

 they connect with capillaries of the medulla. New cells may form 

 by mitosis in the glomerulosa and outer medulla of a mature gland, 



