416 



THE ORGANS 



close relation to the sympathetic, is that their cells take a yellowish 

 brown stain when placed in solutions of chromic acid or chrome 

 salts, retaining the color even after prolonged washing in water. For 

 this reason the cells are sometimes referred to as chromaffin cells and 

 the organs as chromaffin organs} 



While each organ -has its own peculiar structure, all agree in 

 certain general features, (i) The cells are polyhedral and have a 

 general arrangement into cord-like structures rather than into lobules; 

 (2) they are all ductless glands; (3) the cells lie in very close relation 



I 



*E^^gi;,^ Septum.- 



Trabecula of 

 cells in cross- 

 section. 



Distended 

 blood capil- 

 laries. 



Sci.^^- Efferent vein. 



Fig. 293. — Section of human carotid gland. X 160. (Schaper.) 



to rich capillary networks of large vessels, some of which resemble 

 sinusoids and have been described as having incomplete walls, the 

 gland cells thus being in direct contact with the blood stream; (4) 

 unstained the cells show a clear, highly refractive cytoplasm, but con- 

 tain secretion granules which stain yellowish brown with chromic acid 

 and chrome salts, red with safranine, and black with osmic acid; 

 (5) all, as far as has been determined, produce an internal secretion 

 which passes directly into the blood and which acts as a regulator of 

 vascular tone. 



The Carotid Glands. — These are two small ductless glands, each 

 about the size of a rice grain, which lie one on either side of the 



^ Cells containing chromal^in granules have also been described as occurring in 

 sympathetic ganglia, and by Rose as present in many different organs, e.g., the ovary, 

 testicle, blood-vessel walls, etc. 



