Cytomorphosis of Human Testicular Cells 89 



interior becomes fixed to that portion of the wall of the 

 vesicle that is attached to the nuclear membrane. The Golgi 

 complex thereafter remains closely applied to the surface of 

 the acrosomal vesicle (Fig. 3) and gives rise to numerous 

 vacuoles which are believed to coalesce with the vesicle, 

 contributing in this way to its progressive enlargement. The 

 acrosomal granule also grows, seemingly, by addition of 

 material to its surface from the surrounding fluid. The 

 granule at first is almost spherical in shape and projects well 

 into the vesicle, but later it becomes flattened and frequently 

 occupies a shallow depression in the end of the nucleus (Figs. 

 2 and 3). As the area of contact between the enlarging acro- 

 somal vesicle and the nuclear membrane increases, a layer of 

 dense granular material is deposited on the inner aspect of 

 that part of the nuclear membrane which is covered by the 

 vesicle (Figs. 4, 5 and 6). The vesicle gradually extends down 

 over the end of the nucleus like a double-layered stocking 

 cap and, as it does so, its lumen is reduced to a narrow cleft 

 (Figs. 4 and 5). Meanwhile, in the elongation of the spermatid, 

 the Golgi complex and the associated cytoplasm migrate to 

 the posterior pole of the nucleus and the plasma membrane 

 at the anterior end of the cell is brought into close contact with 

 the outer membranous wall of the acrosomal vesicle or head 

 cap. The substance of the granule, which originally was con- 

 fined to the anterior pole of the nucleus, now spreads laterally, 

 filling the narrow cleft between the layers of the cap until it 

 extends all the way to the posterior margin. The head cap at 

 this stage, therefore, consists of outer and inner membranes 

 which are continuous at the posterior margin of the cap, and 

 between these is a thin layer of homogeneous material derived 

 from the substance of the acrosomal granule (Figs. 6 and 7). 



Thus, the study of electron micrographs has clarified the 

 nature of the idiosome and has reaffirmed the origin of the 

 acrosome from the Golgi complex; it has established that 

 the acrosomal vacuole or vesicle is not a fixation artifact but 

 is a real structure which has an important role in the forma- 

 tion of the head cap of the spermatozoon. 



