Cytomorphosis of Human Testicular Cells 93 



The mature Ley dig cells are epithelioid in shape but their 

 membranes are not closely coherent as in epithelial tissues. 

 The nuclei are round and have prominent nucleoli. The 

 cytoplasm is not fibrillar, but, instead, has a vesicular 

 character, owing to the presence of very numerous small 

 membrane-limited vacuoles 100 to 200 millimicrons in dia- 

 meter (Fig. 11). Some of these seem to have a content of very 

 low density but the majority appear quite empty. Their 

 origin and significance is by no means clear. Their mem- 

 branous wall is sometimes observed to be continuous with the 

 plasma membrane in a manner which suggests that they 

 either are formed at the cell surface or discharge their con- 

 tents there. In some Leydig cells these minute vesicles are 

 present in moderate numbers, while in others they are so 

 closely packed that little background cytoplasm can be seen 

 between them. It is easy to speculate that they are somehow 

 related to the specific function of the Leydig cells and that the 

 variations in their abundance from cell to cell reflect different 

 states of physiological activity. 



The mitochondria are not particularly abundant in Leydig 

 cells and are quite variable in shape. Some are elongated, 

 some spherical, and others have a bizarre, swollen appearance. 

 This pleomorphism is consistent with reports, based upon 

 light microscopy, that the mitochondria of interstitial cells 

 are especially labile and very apt to assume enlarged and 

 distorted forms as a result of delayed fixation (Duesberg, 

 1918). The mitochondrial matrix is of very low density 

 and the folds of the membrane projecting into the interior 

 of the organelle are fewer and more irregular in their dis- 

 tribution than in the mitochondria of most other tissues. In 

 keeping with the acidophilic staining of these cells in ordi- 

 nary histological preparations, the endoplasmic reticulum or 

 ergastoplasm is poorly developed and the small particles 

 of ribonucleoprotein, which are responsible for cytoplasmic 

 basophilia (Palade, 1955), are present in small numbers. 



Lipid occurs in the Leydig cells in two forms : homogeneous, 

 moderately osmiophilic droplets (Fig. 8), and heterogeneous 



