THE CAROTID GLAND 



569 



as the original source of leukocytes. Th 

 portions of the lobules; the medulla doi 

 ters of lymph nodules, but is probably 

 The thytnus does not seem to be an org* 

 dogs and guinea pigs is not followed by 

 evidence indicates a reciprocal function 

 and certain of the organs of internal s 

 This suggests a secretory role; a cone 

 the recent experiments of Gudernatsch 



5 proliferative foci are the cortical 



! not correspond to the germ cen- 

 an area of leukocyte dissolution, 

 n essential to life. Extirpation in 

 death. However, the experimental 

 1 relationship between the thymus 

 cretion, especially the sex-glands, 

 ision supported by the results of 

 (Amer. Jour. Anat., 15, 4, 1914) 



in which thymus fed to frog tadpoles, Accelerated growth, but suppressed 

 differentiation. 



V. THE CAROTID GLAND 



This body was first carefully described by Luschka (1862) and, 

 from its intimate relation to the blood-vessels and nerves, is also known 

 as the glomus caroticum or ganglion inter car oticum. It is about the 

 size of a rice grain. It 

 consists of scattered 

 masses of epithelioid cells, 

 usually grouped in small 

 spheroidal clumps or 'cell 

 balls/ embedded in the 

 connective tissue at the 

 point of bifurcation of the '^ % M 



common carotid artery. Am 



Kohn (Arch. f. Mik. 1\?/ 



Anat., 1900) has de- <S^ 



scribed four types of the chrg 



gland according to the FIG. 489.-CAROTm GLAND OF AN APE. 



density of its parenchyma c ^ a < chromaffin ceir . s> connect ive tissue 

 -the type found in man septum. Portions of two adjacent lobules are in- 

 consists of scattered cell eluded in the figure. X 200. (After Kohn.) 

 groups ; in the rabbit they 



are even more diffuse. The carotid gland of a cat consists of a single cell 

 mass, while that of the ape is intermediate between that of the cat 

 and man. 



The glandular elements are derived from embryonal sympathetic 

 ganglion cells (Kohn). They are ovoid cells with finely granular 

 cytoplasm and a spheroidal, somewhat vesicular nucleus. Many of them 

 contain chromamn granules. Because of its genetic relationship and 



