THE CAROTID AND COCCYGEAL BODIES 253 



though he is opposed to the view that the chromaphil tissues 

 are of a secretory nature. 



The cell body is finely and uniformly granular. The nucleus 

 is large, granular, and shows a distinct nuclear membrane and 

 nucleoli. As a rule there is one nucleus, but there may be 

 two. In some cells the nucleus is so poor in chromatin that 

 the cell resembles a nerve cell. Many cells, moreover, possess 

 a cell membrane. 



According to Kohn all the true specific cells of the body are 

 chromaphil cells that is to say, they become stained of a 

 yellowish or brownish tinge by solutions containing bichro- 

 mate of potassium. Kohn states that the degree of coloration 

 varies within very wide 



limits. The cells are '&fy*^Q^*-Ji 



arranged in groups, and 

 the body is permeated 



by non -medullated >\f~^' ft \L j)^ 



nerve fibres and scat- '^>(5^^jfe^^'?*^65^^^ 

 tered nerve cells. &J!r)t'^ J ^J&ffiH^'\ 



The organ is richly ^* O c * ^^Qfcfmfi s ^'*-*'~ 



provided with blood- <l "/ r> V* 



vessels. The arteries 

 break up into a close 



.,, , FIG. 56. Portion of a section through the 



Capillary network, carotid body of a cat. (Drawn by Mrs. 



which penetrates the Thompson.) 



cell groups, and where 



the amount of connective tissue is small, come into close 



contact with the cells. 



Kohn lays great stress upon the intimate relation existing 

 between the nerve fibres in the body and the specific carotid 

 cells. 



The carotid body is developed from the embryonic ganglion 

 cells of the intercarotid sympathetic plexus. 



From the foregoing account it would seem that we are 

 justified in including the carotid body in the category of the 

 chromaphil tissues. The body, then, has no special functions, 

 other than those of the chromaphil tissues generally, and all 

 that has been said on the pharmacodynamical effects of 

 adrenin, the chemistry of adrenin, and the functions of the 

 adrenal medulla, applies in all probability to the carotid 

 body. 



