33 2 



HISTOLOGY. 



The cortical substance consists of cuboidal cells which in the outermost 

 zone are arranged in rounded masses; in the middle zone they form cylin- 

 drical columns; and in the deepest layer the cords unite in an irregular 

 network. The cortex is therefore divided into a zona glomerulosa, zona 

 fasciculata and zona reticularis (Fig. 387). The cells of the cortex are 

 about 15 fjL in diameter and contain fat droplets causing the macroscopic 

 yellow appearance. The drops are especially large in the zona fasciculata 

 (Fig. 388), and are small or even absent in the zona reticularis. The 

 dark brown color of the latter is due to pigment which becomes con- 



Medulla. 



Zona glomerulosa 



Zona fasciculata 



Zona reticularis. 



Cell cords of the- 

 medulla. 



Nerve in cross . 

 section. 



Ganglion cells. ' 



Bundles of smooth muscle 

 fibers in cross section. 



Veins. 



FIG. 387. SECTION OF A HUMAN SUPRARENAL GLAND. X 50. 



spicuous only in the adult. Besides vacuoles the protoplasm of the outer 

 cells contains granules; the nuclei of the glomerular zone may be denser 

 than those of the fascicular layer. The cell columns are in close relation 

 with the endothelium of the blood vessels. They have no basement 

 membrane, and are separated from the vessels by a very slight amount 

 of reticular tissue. 



The medullary substance consists of chromaffine cells arranged in 

 elongated strands which unite and form a network. The cells are very 

 delicate and easily become stellate by shrinkage even in well fixed prepara- 

 tions. They have round nuclei and granular protoplasm but their specific 



