1138 



THE URINARY ORGANS. 



around the suprarenals. The smaller of these, on section, show a uniform surface, 

 but in some of the larger a distinct medulla can be made out. 



On making a perpendicular section, the gland is seen to consist of two 

 substances external or cortical and internal or medullary. The former, 

 which constitutes the chief part of the organ, is 

 of a deep-yellow color. The medullary sub- 

 stance is soft, pulpy, and of a dark-brown or 

 black color, whence the name atrabiliary cap- 

 sides formerly given to these organs. In the 

 centre is often seen a space, not natural, but 

 formed by the breaking down after death of the 

 medullarv substance. 



Capsule. 



Zona 

 glomerulosa. 



Zona retieularit. 



Medulla. 



ipillary. 



FIG. 727. Vertical section of the suprarenal 

 capsule. From Elberth, in Strieker's Manual. 



The cortical portion consists chiefly of narrow columnar masses placed perpen- 

 dicularly to the surface. This arrangement is due to the disposition of the cap- 

 sule, which sends into the interior of the gland processes passing in vertically and 

 communicating with each other by transverse bands so as to form spaces which 

 open into each other. These spaces are of slight depth near the surface of the 

 organ, so that ,there the section somewhat resembles a net ; this is termed the 

 zona glomerulosa ; but they become much deeper or longer farther in, so as to 

 resemble pipes or tubes placed endwise, the zona fasciculate. Still deeper down. 

 near the medullary part, the spaces become again of small extent; this is named 

 the zona reticularis. These processes or trabeculse, derived from the capsule and 

 forming the framework of the spaces, are composed of fibrous connective tissue 

 with longitudinal bundles of unstriped muscular fibres. Within the interior of 

 the spaces are contained groups of polyhedral cells, which are finely granular m 

 appearance, and contain a spherical nucleus, and not unfrequently fat-molecules. 

 These groups of cells do not entirely fill the spaces in which they are contained, 



