STRUCTURE OF THE SUPRARENAL CAPSULES. 



415 



Fig. SOL 



The fibrous investment (fig. 301, a), is so intimately connected with 

 the deeper parts that it cannot be removed without lacerating the sub- 

 jacent structure. Its deeper la^-ers are destitute of elastic fibres, and 

 are particularly rich in connective tissue corpuscles : they are continuous 

 with the septa which enter into the formation of the substance of the 

 organ. 



The cortical part of the supra- 

 renal body, examined in a section with 

 a low magnifying power (fig. 301, 1), 

 is seen to consist of a fibrous stroma, 

 in which are imbedded column-like 

 groups of cells. The groups measure 

 on an average -T-Joth of an inch in 

 diameter, and are arranged vertically 

 to the surface of the organ. In the 

 deepest part of the cortex, however, 

 the colour is darker, and the columnar 

 arrangement is lost, the stroma being- 

 more equally distributed (d) ; and 

 immediatel}' beneath the fibrous coat 

 there is another narrow zone in 

 wliich the stroma forms oval spaces, 

 of which it is difficult to say 

 whether they communicate with the 

 extremities of the columns or not (Z*). 

 These inner and outer layers have 

 been named "by J. Arnold respec- 

 tively zona reticularis and zona glo- 

 merulosa, while he applies the term 

 zona fasciculata to the main part(c) ; 

 but the transition from one of these 

 parts to another is not sudden nor 

 indicated by any line of demarcation. 



The cells which form the groups 

 and columns of the cortical substance 

 are polyhedral in form (fig. 302) : 

 their protoplasm is finely granular 

 but not unfrequently contains yel- 

 lowish oil globules. The cells vary 

 from aijW^'li to TTrVo^h of an inch 

 in size : each has a clear round 

 nucleus. 



The small arteries, entering from 

 the surface, run parallel to these 

 columns, frequently anastomose to- 

 gether between them, and surround 



each column of cells with a fine capillary network. Small bundles of 

 nerves pass inwards in the septa between the columns to reach the 

 medullary part of the organ, and their fibres begin to spread out in 

 the zona reticularis, but do not appear to be distributed to the cortical 

 substance. 



The medullary part (fig. 301, 2) of the suprarenal capsule is 

 marked off fi'om the cortical part by a layer of loose connective tissue. 





m 



J 



Fig. 301. — Vertical Section of supra- 

 renal Body : Human. Magnified 

 (Ebertli). 



1, cortical substance ; 2, medullaiy 

 substance : a, capsule ; b, zona glome- 

 rulosa ; c, zona fasciculata ; d, zona re- 

 ticularis ; c, groups of medullary cells ; /, 

 section of a lar^e vein. 



