26 ANATOMY 



from the adrenal (or suprarenal) plexus and are probably all 

 postganglionic and unmyelinated. 179 



The efferent nerves of the adrenal are not accurately known. 

 Elliott 179 assumes the existence of a center controlling epineph- 

 rine discharge near the bulbar vasomotor centers. Others 

 place it in the subthalamic region. 419 



THE CHROMAPHIL TISSUE 



The medulla of the mammalian adrenal and its homologues 

 in the lower animals are components of the chromaphil system. 

 The tissue comprising this system is characterized by the 

 brownish discoloration which it undergoes when fixed in a 

 chromate solution. Stilling 596 in 1890 observed that this 

 chromaphil reaction was given not only by the adrenal medulla 

 but also by groups of cells associated with the sympathetic 

 nervous system. Stilling applied the generic term "chromo- 

 phil" to these cells which Vincent 649 altered to the more euphe- 

 mistic expression "chromaphil." Kohn, 357 who applied the 

 term chromaffin to these cells, introduced the term "para- 

 ganglia" to denote the cells found in association with the 

 sympathetic nervous system. 358 The adrenal medulla itself 

 was indicated by Kohn as the "paraganglion suprarenale." 

 Kohn also called attention to the conspicuous strip of chroma- 

 phil cells situated ventral to the abdominal aorta and superior 

 to the inferior mesenteric artery. He named this tissue the 

 "paraganglion aorticum ahdominale" Zuckerkandl 697 discov- 

 ered a pair of similarly staining bodies in the region of the 

 inferior mesenteric artery of the new born. These bodies are 

 known as the organs of Zuckerkandl. 



The paraganglia are small round masses, 1 to 3 mms. in 

 diameter, placed within or contiguous to the capsules of the 

 ganglia of the sympathetic system. Usually one paraganglion 

 is associated with each ganglion of the coeliac, renal, adrenal, 

 aortic, and hypogastric plexuses. Sometimes they are also 

 associated with the ganglia of the cardiac and inferior mesen- 



