46 



PHYSIOLOGY 



CHAP. 



histology, and experimental physiology, to be organs entirely 

 similar to the medullary substance of the suprarenal bodies. 



Chromamne or " paragangliar " tissue is thus closely related to 

 the nerve cells of the sympathetic system, being in fact differ- 

 entiated from the same embryonic group of cells. In adult 

 animals it is still intimately connected with the sympathetic 



a.r. 



FIG. 13. (Left.) Parasympathetic bodies of Zuckerkandl (human). From an anatomical pre- 

 paration of Sperino and Balli. A, aorta; V, vena cava ; ar, left renal artery; vr, left renal 

 vein ; op, parasympathetic bodies, or paraganglia ; a' v', artery and vein of right paraganglion ; 

 a"v", artery and vein of left paraganglion; mi, inferior mesenteric artery; v.sp, spermatic 

 or ovarian vein ; pla, aortic plexus of sympathetic. 



FIG. 14. (Right.) Paraganglion of adult cat. (A. Kohn.) A, aorta ; B, vena cava; C, suprarenal 

 capsule ; D, caeliac ganglion ; S, sympathetic ; P, abdominal aortic, filiform paraganglion ; 

 p, punctiform paraganglia. 



system, many ganglion cells being mixed with the cells of 

 the medullary substance of the suprarenal bodies, while nodules 

 of chromaffine tissue adhere to the sympathetic chain in various 

 regions (Fig. 14). Chromaffine tissue has accordingly been defined 

 as " an epithelial tissue of neural origin " (Diamare). 



Functionally, too, we shall find an intimate relation between 

 the sympathetic system and the product of the internal secretion 

 of chromaffine tissue. 



The arteries that supply the suprarenals penetrate the cap- 



