94 Don W. Fawcett and Mario H. Burgos 



aggregates of intensely osmiophilic, granular material (Fig. 9). 

 The former are interpreted as droplets of neutral fat, while 

 the latter are believed to belong to the group of acetone- 

 insoluble lipid complexes often referred to as lipochrome 

 pigments or ceroid. The intensely osmiophilic granular 

 material is often aggregated around the periphery of vacuoles 

 of a homogeneous substance which does not reduce osmium. 

 Sharp angular clefts which sometimes occur in the midst of 

 these conglomerations are interpreted as negative images 

 of crystals which have been dissolved out during specimen 

 preparation. The significance of these pigment masses is not 

 clear, but they are of very common occurrence in the cells 

 of most steroid-producing endocrine glands. The amount of 

 lipid present in the mature Leydig cells is highly variable. 

 Some of them are virtually devoid of droplets of neutral fat 

 but contain considerable pigment. Others have large amounts 

 of both. 



In electron micrographs, the crystalloids of Reinke have a 

 complex and highly-ordered internal structure which presents 

 a regular pattern bearing a superficial resemblance to that 

 of a woven fabric (Fig. 14). The pattern varies, depending 

 upon how the object is cut, but in crystals which are most 

 favourably oriented with respect to the plane of section, it is 

 possible to resolve a pattern of densities 100-150 A in dia- 

 meter, uniformly spaced about 190 A apart along two axes 

 which are approximately at right angles to one another (Fig. 

 15). The length of the period along the third axis has not been 

 determined. This pattern is thought to represent the arrange- 

 ment of macromolecules in the lattice of a protein crystal. 

 A few of the crystals are rectilinear, with straight sides and 

 sharp angles, but the majority have rounded contours, parti- 

 cularly at the ends (Fig. 13). There are indications that they 

 are almost as soft as the surrounding cytoplasm for, when 

 sectioned, they cut perfectly smoothly without tearing or 

 setting up vibrations in the block. Protein crystals are apt 

 to be rounded at the ends rather than sharp-angled and, in the 

 "wet" state, they are quite soft. 



