HISTOLOGY 



Long meshed 

 capillary net of 

 the cortex. 



421). These are the cells which are believed to produce adrenalin; the 

 function of the cortical cells remains unknown. 



The capsule of the suprarenal glands is a connective tissue layer, said 

 to contain smooth muscle fibers and small ganglia, in addition to vessels and 

 nerves. Around the blood vessels especially, it contains elastic tissue. 

 The capsule sends slender prolongations into the gland, and elastic tissue 

 occurs in the medulla. The cortex contains very few if any elastic fibers, 

 and its framework appears to consist of reticular tissue. 



The arteries supplying the suprarenal glands are from several sources. 

 They divide into many small branches in the capsule, and these penetrate 

 the cortex, forming a long- meshed capillary network (Fig. 422). In the 



medulla the meshes be- 

 come round and the 



T^^^M^^H^^^^^I ^HH 



Artery. sfl vessels collect to form 



veins, the larger of which 

 are accompanied by lon- 

 gitudinal strands of 

 smooth muscle fibers. 

 Some arteries are said to 

 pass directly from the 

 capsule to the medulla, 

 without branching in the 

 cortex. Within the med- 

 ulla the veins unite to 

 form the central veins, 

 which are the main stems 

 of the suprarenal veins 

 (Fig. i68,p. 173). They 

 emerge at the hilus; the right empties into the inferior vena cava and the 

 left joins the left renal vein. 



Lymphatic vessels have been found in the capsule, where they may 

 drain the cortex, and also in the medulla, emerging at the hilus. 



The numerous, mostly non-medullated nerves, of which a human 

 suprarenal gland receives about thirty small bundles, proceed chiefly from 

 the cceliac plexus and pass with the arteries from the capsule into the med- 

 ulla. Within the capsule they form a plexus, from which branches de- 

 scend into the zona glomerulosa and zona fasciculata; there they end on the 

 surface of groups of epithelioid cells, without penetrating between the in- 

 dividual cells. The plexus in the zona reticularis is more abundant, and is 

 formed from fibers which descend directl thryough the outer zones; its 

 fibers likewise terminate on the outer surface of groups of cells. In the 

 medulla, the nerves are extraordinarily abundant and each cell is sur- 

 rounded by nerve fibers. Groups of sympathetic ganglion cells are found 



Round meshed 

 net of the 

 medulla. 



J 



Vein of the 



medulla. 



FIG. 422. FROM A SECTION OF AN INJECTED SUPRARENAL GLAND OF 

 A CHILD. X 50. 



