426 



E. V. COWDRY 



their concavity, as is the case in leukocytes. In cells with a single nucleus 

 two centrosomes may occur, and in binucleated cells as many as four may 

 be seen. There is no radial arrangement of cytoplasmic granules about 

 the centrosome to indicate that it is a dynamic center. 



Fat Inclusions, Fat granules occur in the interstitial cells in vari- 

 able amount, especially in man. They are said to increase with age, and 

 occur in clumps distributed without apparent order in the cytoplasm. 



Pigment. Pigment granules begin to appear at about twenty-one 

 years of age and become quite abundant. According to Lehrt the pigment 

 is a lipochrome. Owing to the fact that there is often a sharp contrast 

 between pigmented and non-pigmented cells in the same testicle, it has 



Fig. 2. interstitial cells in the testis of the opossum showing the range of varia- 

 tion in the structure of the Golgi apparatus, after Duesberg. 



been claimed that, the pigmented cells are undergoing degeneration, though 

 there is no noticeable difference in the size of the cells or in the nucleus- 

 cytoplasmic ratio. Mitochondrial changes have not been studied as indi- 

 cators of this supposed degeneration. In the horse fetus the pigmented 

 cells are very discrete and are called by Bouin and Ancel ((j) ''cellules Ti 

 ganulations xanthiqnes." 



Reticular Apparatus. Duesberg alone has studied the reticular ap- 

 paratus in the interstitial cells of the opossum by means of Cajal's uranium 

 nitrate method. He has found that it varies between the extremes illus- 

 trated in Fig. 2. Inasmuch as no trace of this complicated network can 

 be seen in the living unstained cells, considerable caution must be exer- 

 cised in its interpretation. This much may be said, however, that it must 

 indicate some regional variation in the properties of the cytoplasm, be- 

 cause the location of the network is quite definite, being in close associa- 

 tion with the centrosome. 



