OVUM-LIKE BODIES IN THE TESTIS 571 



togenesis. Mitotic figures are rare. The lumina are occupied 

 by a protoplasmic syncitium. The nuclei of the epithelial cells 

 are mostly arranged in a single peripheral layer, although many 

 lie more centrally. In the majority of cells the outline of the 

 cytoplasm is indistinguishable as these cells tend to coalesce 

 laterally. Others, however, are clearly defined. 



The epithehal cells appear to be of three types as follows : 



(1) Typical spermatogonia. These contain a reticulate nucleus 

 with well-marked nucleolus. The limits of the cytoplasm in 

 neighbouring cells cannot be made out. 



(2) Large cells lying immediately central to the basal layer. 

 They may be twice or three times as large as the basal cells. 

 The cytoplasm is very hyaline and the cells in consequence are 

 sharply demarcated from the more darkly-staining surrounding 

 tissue. The nucleus varies in size and staining capacity. 

 Typically it is finely reticulate and contains a nucleolus. It 

 may, however, be small and dense, or so large as to fill two- 

 thirds of the cell. In the latter case the chromatin material 

 is reduced to a few small strands and granules surrounding 

 a very large nucleolus (PI. 18, fig. 2). 



These large clear cells are probably late spermatogonia. 

 Many appear degenerate, and in a few the nucleus is altogether 

 disintegrating. It is noticeable that the larger the cell the 

 greater is the relative size of the nucleolus. This fact will 

 be referred to later. 



(3) The third type of cell has a rather small granular ovoid 

 nucleus containing a nucleolus. The cytoplasm is pyramidal in 

 form. It is attached at the base to the basement membrane 

 and is often drawn out into a protoplasmic filament. These 

 we regard as cells of Sertoli. The lumina of the tubules often 

 contain a deeply-staining amorphous substance which appears 

 to be a mixture of protoplasmic detritus and coagulated fluid. 

 Degenerate nuclei are usually present in such masses (PI. 22, 

 fig. 19). Small deeply-staining globular bodies (PI. 22, fig. 20) 

 occasionally occur in the central syncitium of the tubules and 

 more rarely among the peripheral cells. They are found to 

 stain brightly with the Orange G. of Mallory's stain. It would 



