180 The Development of the Interstitial Cells of Leydig 



stages there are many cells of the germinal epithelium loaded with large 

 grannies, bnt as will be seen later, they certainly are not fat. 



With respect to the primitive seminal tubules it was found that sec- 

 tions of Flemming material, stained with iron-hsematoxylin, showed 

 many black particles, whereas the same material unstained showed very 

 few, or none at all, until the length of 3.5 cm. was reached. It was not 

 until a still later stage was reached that fat could be demonstrated with 

 Sudan III. Making allowances for imperfection of technique, it hardly 

 seems possible that fat could have been present in such large quantity 

 as to constitute a veritable fatty degeneration, and have escaped detection 

 by both the osmic and the Sudan III, especially as each reagent gave 

 good results in later stages. In the light of recent studies of fat meta- 

 bolism the presence of some fat in these cells would not seem patho- 

 logical. In pigs of 8 cm. fat is present in the seminal tubules in the 

 form of quite distinct globules, and remains present in that shape 

 through all the remaining stages of their embryonic development. 



In the case of the Leydig's cells I could not positively demonstrate a 

 fatty content in pigs under 14 cm. in length. Small globules of fat 

 appear a little later, and are fairly abundant in the Leydig's cells of the 

 28 cm. embryo. In all cases they are minute droplets situated in the 

 vicinity of the nucleus, and not in the vacuoles previously described. It 

 may be noted here that Plato (second reference) found very little fat 

 in the Leydig's cells of the wild boar. 



The Granules of the Germinal Epithelium. — As previously stated, 

 many of the cells which compose the germinal epithelium in pigs of the 



various lengths from 2 cm. to 

 4 cm. are loaded with large gran- 

 ules (Fig. 10). While they were 

 first noticed in sections prepared 

 by Mallory's method, they are 

 quite distinct in all the different 

 PIG. 10. Pig 25 mm. Perit.meai epithe- metliods employed. Inuustaincd 

 Co^gJ^rld. x'^so'a"" ^""^ ^'^°'^*°''y"° ^"""^ sections they appear as colorless, 



homogeneous, glistening, more or 

 less circular bodies. They are unaffected by agents which dissolve fat, 

 such as ether and absolute alcohol. In preparations stained with iron- 

 hffimatoxylin they appear intensely black. They also stain well with 

 the aniline-blue in Mallory's method, and in general are acidophile, 

 though they can be stained faintly by gentian violet in Weigert's 

 method for fibrin. Occasionally a group of them is seen in a cell which 

 has wandered down from the germinal epithelium into the albuginea; 



