THE SUPRARENAL GLANDS, OR ADRENAL CAPSULES 1451 



yellow color. The medullary substance is soft, pulpy, and of a dark-brown color. In the 

 centre is often seen a space, not natural, but formed after death by the disintegration of the 

 medullary substance. 



The capsule consists of white fibrous connective tissue in which some smooth muscle tissue 

 is seen. From the capsule and vessel sheaths the framework of the organ is derived. 



The cortical portion consists of epithelial cells arranged in three zones. The zona glomer- 

 ulosa the outermost consists of oval or round cell groups surrounded by capillary plexuses and 

 reticulum. The cells are polyhedral in shape with clear nuclei; the protoplasm is granular and 

 contains many fat globules. The zona fasciculata or middle zone consists of columns of 

 epithelial cells (usually two cells wide) supported by reticulum containing bloodvessels and lym- 

 phatics. These cells resemble the above, but the nuclei are in the peripheral portion of the cells. 

 The zona reticularis, the innermost of the three, consists of anastomosing columns or chains 

 of cells. These cells are smaller than the preceding, are distinct in outline, and possess a 

 granular and pigmented protoplasm. 



-.Capsule. 

 Zona glomerulosa. 

 Zona fasciculata. 



FIG. 1208. Section of human suprarenal gland. (Radasch.) 



The medullary portion (mbstantia medullarw) (Fig. 1208) is usually separated from the 

 cortex by a layer of large smooth cells. Beneath this layer the epithelial cells are arranged 

 in irregular groups and chains, surrounded by reticulum and capillaries. The cells are small 

 and their outlines are indistinct. They color deeply with chromium salts, and are called 

 chromaffin cells. Many sympathetic nerve cells are present. 



Vessels and Nerves. The numerous arteries which enter the suprarenal bodies from the 

 sources mentioned below form plexuses in the capsule and penetrate the cortical part of the 

 gland, where they break up into capillaries in the fibrous septa, and these converge to the very 

 numerous thin-walled veins of the medullary portion. These veins usually empty directly 

 into the large central veins. The medullary vessels are derived from the cortical vessels, and 

 pass to the medulla without branching to form plexuses of capillaries around the cells. The 

 veins in this region converge to form from two to four central veins, which unite to become 

 the suprarenal vein, which in turn emerges as a single vessel from the centre of the gland. 



The arteries supplying the suprarenal glands are three in number and of large size; they 

 are derived from the aorta, the phrenic, and the renal; they subdivide into numerous minute 

 branches previous to entering the substance of the gland. 



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

 branches from the cortical substance; it emerges from the hilum and opens on the right side 

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



The lymphatics form several collections which are about the beginning of the suprarenal 

 vein. They terminate in the nodes at the corresponding side of the aorta. 



The nerves are myelinated and amyelinated, are exceedingly numerous, and are derived 

 from the solar and renal plexuses, and, according to Bergmann, from the phrenic and vagus 

 nerves. They enter the lower and inner part of the gland. A plexus in the gland sends 

 branches into" the cortex, where plexuses are formed around the vessels. Branches are also 

 sent to the medulla, where rich plexuses are formed around the cells and vessels. Many sym- 

 pathetic ganglia are seen there. 



