96 Don W. Fawcett and Mario H. Burgos 



recognition of senility in cells at the electron microscope level 

 have not yet been established, it is difficult to escape the 

 conclusion that some of the Leydig cells are maturing while 

 others are no longer physiologically active and are, perhaps, 

 in a state of impending degeneration. 



Acknowledgement. 



We are greatly indebted to Dr. Fred A. Simmons of the Department 

 of Gynecology of Harvard Medical School for making available to us 

 the human testicular biopsies upon which this study is based. 



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DISCUSSION 



Montagna: I have scarcely recovered from the breath-taking beauty 

 of these preparations. Before I make any comments (which unfortu- 

 nately have very little to do with Dr. Fawcett's presentation) may I say 

 that I have been accused of dealing only with the testes of feeble-minded 

 individuals. This is largely true because they are the only people we 



