THE SUPRARENAL GLANDS 



551 



At the inner border of the zona fasciculata the connective^ tissue 

 bundles pass insensibly from the regular columnar arrangelnenT of this 

 layer into a reticular maze. The resulting cell groups are of very irregu- 

 lar form and compose the innermost cortical layer, the zone reticularis. 

 This layer is the 

 thinnest and least 

 d is t i n c t of the 

 three zones of the 

 c o r t e x. It can 

 often be more read- 

 ily distinguished by 

 the highly Ipig- 

 mented condition 

 of its cells, than by 

 the mere form of 

 its cell columns. 

 In man it ; passes 

 almost insensibly 

 into the medulla ; 

 in many animals 

 e.g., the dog, cat, 

 and pig there is a 

 sharp demarcation 

 between the zona 

 reticularis and the 

 medulla, produced 

 by a thin mem- 

 branous layer / of 

 connective tjssue 

 which apparently 

 results from It h e 

 fusion of the , cen- 

 tral ends of j the 

 fibrous bands $1 the 

 cortical stroma. Such a membranous septum is usually wanting in the 

 human adrenal. 



The connective tissue stroma of the adrenal consists of a delicate 



vascular network, which in the cortex contains very few if any~elastic 



fibers. Flint (1900) has shown that this connective tissue is, in large 



part, at least, ^reticular tissue. The capsule consists of dense bundles 



35 



FIG. 479. PHOTOMICROGRAPH OF SUPRARENAL GLAND OP 

 DOG. Magnification X 30. 



A, loose areolar connective tissue of outer portion of 

 capsule containing two large (G) and several small gan- 

 glia; c, capsule proper; g, zona glomerulosa; F, zona fascic- 

 ulata; R, zona reticularis of cortex; M, medulla, showing 

 the large central vein (F). 



