1280 



SPLANCHNOLOGY 



The cortical portion (substantia corticalis) consists of a fine connective-tissue net-work, in 

 which is imbedded the glandular epithelium. The epithelial cells are polyhedral in shape and 

 possess rounded nuclei; many of the cells contain coarse granules, others lipoid globules. Owirg 

 to differences in the arrangement of the cells, three distinct zones can be made out: (1) the zora 

 glomerulosa, situated beneath the capsule, consists of cells arranged in rounded groups, with 

 here and there indications of an alveolar structure; the cells of this zone are very granular, and 

 stain deeply. (2) The zona fasciculata, continuous with the zona glomerulosa, is composed of 

 columns of cells arranged in a radial manner; these cells contain finer granules and in many 

 instances globules of lipoid material. (3) The zona reticularis, in contact with the medulla, 

 consists of cylindrical masses of cells irregularly arranged; these cells often contain pigmer.t 

 granules which give this zone a darker appearance than the rest of the cortex. 



The medullary portion (substantia medullaris) is extremely vascular, and consists of large 

 chromaphil cells arranged in a network. The irregular polyhedral cells have a finely granular 

 cystoplasm that are probably concerned with the secretion of adrenalin. In the meshes of the 

 cellular network are large anastomosing venous sinuses (sinusoids) which are in close relationship 

 with the chromaphil or medullary cells. In many places the endothelial lining of the blood sinuses 

 is in direct contact with the medullary cells. Some authors consider the endothelium absent in 

 places and here the medullary cells are directly bathed by the blood. This intimate relationship 

 between the chromaphil cells and the blood stream undoubtedly facilitates the discharge of the 

 internal secretion into the blood. There is a loose meshwork of supporting connective tissue con- 

 taining non-striped muscle fibers. This portion of the gland is richly supplied with non-medullated 

 nerve fibers, and here and there sympathetic ganglia are found. 





Zona fasciculate 



1 1 Zona reticularis 



' Multinucleated mass 

 '* of protoplasm 



- Medulla 



Ganglion 



PIG. 1185. Section of a part of a suprarenal gland. (Magnified.) 



Vessels and Nerves. The arteries supplying the suprarenal glands are numerous and of 

 comparatively large size; they are derived from the aorta, the inferior phrenic, and the renal. 

 They subdivide into minute branches previous to entering the cortical part of the gland, where 

 they break up into capillaries which end in the venous plexus of the medullary portion. 



The suprarenal vein returns the blood from the medullary venous plexus and receives several 

 branches from the. cortical substance; it emerges from the hilum of the gland and on the right 

 side opens into the inferior vena cava, on the left into the renal vein. 



The lymphatics end in the lumbar glands. 



The nerves are exceedingly numerous, and are derived from the celiac and renal plexuses, 

 and, according to Bergmann, from the phrenic and vagus nerves. They enter the lower and 

 medial part of the capsule, traverse the cortex, and end around the cells of the medulla. They 

 have numerous small ganglia developed upon them in the medullary portion of the gland. 



In connection with the development of the medulla from the sympathochromaffin tissue, it is 

 to be noted that this portion of the gland secretes a substance, adrenalin, which has a powerful 

 influence on those muscular tissues which are supplied by sympathetic fibers. 



