328 



PHYSIOLOGY OF GONADS 



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Fig. 5.11. Spermiogenesis of the mouse as seen with PAS-hematoxyhn staining of Zenker- 

 formol fixed testis. Drawings are arranged in a spiral to demonstrate stages which overlap 

 in a cycle of the seminiferous epithelium. Orientation of spermatids in relationship to the 

 basement membrane also is shown. ^ to S is the Golgi phase, 4 to 7 the cap phase, 8 to 12 the 

 acrosome phase, and 13 to 16 the maturation phase. (From E. F. Oakberg, Am. J. Anat., 

 99, 391, 1956.) 



terone can maintain spermatogenesis if it 

 is administered within a month after hy- 

 pophyscctomy but cannot if treatment is 

 delayed more than a month may not be 

 so puzzling if it is assumed that androgen 

 protects in some way the serious depletion 

 of spermatocytes at meiosis. 



The plan of spermiogenesis in many spe- 

 cies is essentially similar to that in the 

 rat and mouse. Clermont (1954) found that 

 the hamster shows the same successive 

 stages of spermatogenesis except that five 

 cycles may be represented simultaneously. 

 In the mouse, Oakberg (1956a, b) described 

 16 stages, the first 12 of which constitute a 

 cycle (Fig. 5.11 and Table 5.2). Four cycles 

 constitute complete spermatogenesis and re- 

 quire 34.5 days. Generally, the same plan 

 of spermiogenesis holds for the guinea pig, 

 cat, bull, dog, ram, monkey (Fig. 5.12), and 



man (Leblond and Clermont. 1952b; Cler- 

 mont and Leblond, 1955) , although many 

 differences in cytologic detail exist and have 

 been documented (Zlotnik, 1943; Gresson, 

 1950; Gresson and Zlotnik, 1945, 1948; Bur- 

 gos and Fawcett. 1955; Watson, 1952; 

 Challice, 1953). 



Application of quantitative studies to hu- 

 man spermatogenesis has, to date, been dis- 

 appointing. Spermatogenesis does not pro- 

 ceed along a wave, nor are the various stages 

 sharply delimited, as they are in the rat. 

 Further, the testis of the human also differs 

 from that of the rat in that the relative pro- 

 })ortion of differentiated germ cells to sper- 

 matogonia is less. No helpful findings in 

 cases of human infertility have been ob- 

 tained by quantitative analysis of the 

 germinal epithelium (Roosen-Runge and 



