THE SUPRARENAL GLANDS 



1323 



Stohr and his followers as modified epithelial elements, not true blood cells. Maurer, Bruant, 

 and Bell regard them as modified epithelial cells which become true functional leucocytes. 



THE CHROMAFFIN SYSTEM 



It has recently been shown that in connection with the ganglia of the sympa- 

 thetic nervous system, special cells, other than the nerve cells, are found. These 

 differ from the nerve cells in that when subjected to the action of chromic acid 

 salts there can be demonstrated in their protoplasm small granules which take on 

 a darker stain. These cells are therefore known as chromaffin cells. The}'-, with 

 the cells of the sympathetic system, are derived from the ectoderm. They ap- 

 pear first as indifferent cells, the sympatho-chromaffin cells. Some of these later 

 develop into sympathetic ganglion cells, others into chromaffin cells. Some of 

 these latter cells remain, isolated or in groups, permanently associated with the 

 sympathetic ganglia, the paraganglia; others become separated and form the 

 medullary portion of the suprarenal glands, the aortic paraganglia, and the 

 glomus caroticum. 



THE SUPRARENAL GLANDS 



The suprarenal glands [glandulae suprarenales] or adrenal glands are small 

 irregularly shaped glandular bodies composed of two quite different organs. 

 In the lower vertebrates these two parts are entirely separated from one another 



Fig. 1077. — The Suprarenal Glands, Ventral View. 



Margo superior 

 Apex suprarenalis 



Margo medialis 

 Hilus 

 Fades anterior 



Vem 



but in man and the mammals they have become joined together one within the 

 other. The external cortical portion, of unknown function, is developed from the 

 mesoderm. The internal medullary portion is derived from the sympatho- 



FiG. 1078. — The Suprarenal Glands, Dorsal View. 



Margo superior 



Apex 



suprarenalis 



Facies posterior 



Margo medialis 

 Facies posterior 



i 



Basis gl. suprarenalis 



chromaffin tissues and thus from the ectoderm in common with the sympathetic 

 nervous system. This part of the suprarenal glands is known to produce an 

 internal secretion which reaches the general circulation through the veins and 



