INTERNAL SECRETION 



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The gland is abundantly supplied with blood-vessels and nerves. The 

 arteries are branches of the aorta, the phrenic, and renal arteries. After 

 penetrating the gland they divide into smaller branches and capillaries which 

 ultimately come into close relation with the cells of both the cortex and 

 medulla. The veins emerge from the gland at the hilum and empty on 

 the right side into the vena cava and on the left side into the renal vein. 

 The nerves passing to the gland are derived for the most part from the 

 autonomic system. The pre-ganglionic fibers pass from the cord by way 

 of the splanchnics to the semilunar ganglion. The post-ganglionic fibers 

 pass from the semilunar ganglion direct to the gland. According, to 

 Bergmann nerves come from the phrenic and vagus also. 



Embryologic Development. Embryologic 

 investigations have shown that the mature adre- 

 nal gland consists of two distinct tissues derived 

 from two different portions of the embryo. The 

 cortex is derived from that portion of the meso- 

 derm from which is evolved the precursor of the 

 kidney, the Wolffian body; the medulla is de- 

 rived from the embryonic sympathetic ganglia 

 and consists primarily of nerve-cells, which, 

 however, in the course of development become 

 profoundly modified. Comparative anatomic 

 studies have shown the relation of these two 

 components of the adrenal body. In the elasmo- 

 branch fishes, the shark, ray, etc., the cortex is 

 represented early by an inter-renal body some- 

 what rod-shaped and elongated and situated to- 

 ward the posterior portion of the kidney. In the 

 bony fishes this organ becomes paired. The 

 medulla is represented by a series of paired 

 bodies extending along the vertebral column 

 and in close relation to the sympathetic ganglia 

 and contain a number of chromaffin cells. 

 These two elements unite to form the com- 

 pound adrenal. In the mammals the larger por- 



tion of this chromaffin material fuses and be- capsule; &, zona glomerulosa; c, 

 comes enveloped on each side by the inter-renal ^afasciculata; ;d, zonareticuiaris; 



, , ,i ,1 r A r ^1 i i i , medullary cords; /. venous cnan- 



body with the formation of the existing adrenal n ' el; ^ ganglion-cells. (Piersol.) 

 body. The unincorporated portions of the chro- 



maffin bodies remain as masses of varying size, found in connection with 

 the sympathetic ganglia. The most important of these bodies is the 

 "abdominal chromaffin body" extending along the aorta from the level of 

 the adrenals to the bifurcation. It is readily exposed in the dog by stain- 

 ing with a solution of bichromate of potassium. Accessory adrenal bodies 

 may consist of either cortical or chromaffin material alone or of both. 



The Effects of Disease. Destructive pathologic processes involving 

 the adrenals cause a profound disturbance of the nutrition first described by 

 Addison and subsequently termed by Trousseau, Addison's disease, which 

 is characterized by extreme muscular weakness and an incapacity for sus- 

 tained muscle activity; a bronze-like discoloration of the skin and mucous 



