Cytomorphosis of Human Testicular Cells 87 



Observations on Spermatogenesis 



The Spermatocyte divisions 



Electron micrographs disclose that, in the division of the 

 secondary spermatocytes, karyokinesis proceeds normally but 

 cytokinesis is delayed. Therefore, binucleate spermatids are 

 fairly common and, in these, differentiation of an acrosome 

 often begins in association with each nucleus before division 

 of the cell body occurs. When constriction does take place, 

 the daughter halves remain connected by a narrow proto- 

 plasmic bridge throughout the early stages of their trans- 

 formation into spermatozoa (Fig. 1). The connection between 

 these cells is somewhat larger than the intermediate body 

 (Zwischenkorper) that is seen in many other cell types during 

 telophase of mitotic division and it persists longer. With the 

 osmic acid fixative used, the bridge contains no visible rem- 

 nants of the spindle apparatus. Although it is true that some 

 of the testicular biopsies examined were obtained from 

 persons being studied clinically for infertile marriage, it is 

 doubtful whether these atypical cell divisions should be con- 

 sidered pathological, for they are seen with about the same 

 frequency in sections of cat testis (Burgos and Fawcett, 1955) 

 and in the monkey, rabbit and toad as well. 



These persisting intercellular connections seem to have been 

 overlooked in studies on mammalian spermatogenesis with 

 the light microscope. However, McGregor (1899) reported 

 that the secondary spermatogonia, primary and secondary 

 spermatocytes and the spermatids of amphiuma are con- 

 nected in pairs or groups of four by "intermediate bodies 

 which persist unusually long after telophase". It is not known 

 at just what stage in the differentiation of the mammalian 

 spermatids they become completely separated from one 

 another. It is tempting to speculate that some of the double 

 anomalies observed among the spermatozoa of the human 

 ejaculate may have their origin in an exaggeration of this 

 normal tendency for the germ cells to remain connected by in- 

 tercellular bridges through the early stages of spermatogenesis 



