60 The Biochemistry of Semen 



glands which elaborate the seminal plasma. In rats after total body 

 exposure to 500 r, there was occasionally a small but transient de- 

 crease in the level of fructose and citric acid secreted by the acces- 

 sory organs but in surviving animals the activity was restored to 

 normal within a few weeks after irradiation. This was a stage when 

 the spermatozoa were mostly immotile and a large proportion of 

 them severely damaged (Lutwak-Mann and Mann, 19506). 



Variations in hydrogen ion concentration and tonicity 



Hydrogen ion concentration is undoubtedly one of the most 

 important factors which influence the motility, viability and meta- 

 bolism of spermatozoa in all species from sea-urchin to man (Cohn, 

 1917, 1918; Wolf, 1921; Gellhorn, 1920, 1927; Healy and Anderson, 

 1922; Mettenleiter, 1925; Barthelemy, 1926; Yamane and Kato, 

 1928; Komatsu, 1929; Schlenk, 1933; Grodzinski and Marchlewski, 

 1935). Most authors agree that a value just above pH 7 provides 

 the optimum for the survival of spermatozoa. Sperm respiration 

 is stated to be optimal at the following pH values, boar 7 •2-7- 5, 

 ram, 70-7-2, bull 6-9-70, cock 7-25, rabbit 6-8 (Winchester and 

 McKenzie, 1941; Lardy and Phillips, 1943«). Below the optimum, 

 motility and metabolism alike decline progressively. Alkalinity on 

 the other hand, up to pH 8-5 and above, has frequently been ob- 

 served to enhance the movement, particularly of human spermatozoa. 

 Whereas in some species including several fishes, the spermatozoa 

 are known to be extremely sensitive to changes in pH, in others, e.g. 

 in the frog, certain birds and mammals, they exhibit a remarkable 

 degree of resistance (Gellhorn, 1920, 1922, 1927). In the case of 

 rabbit sperm partially motile spermatozoa have been found within 

 the range of pH 5-0-8-8 (Cole, Waletzky and Shackelford, 1940). 

 More recently Emmens (1947) has shown that even at pH 9-5-10-0 

 rabbit spermatozoa retain partial motility for several hours, but 

 they become immotile and die rapidly at pH values below 5-8. 

 According to this author, the point at which the progressive move- 

 ment is abolished and motility reduced to a condition where heads 

 become completely stationary but tails still retain feeble motion, 

 coincides with a state when about 50% of the sperm cells can be 

 shown to be dead by the differential staining method of Lasley, 

 Easley and McKenzie (1942); in this method, dead spermatozoa take 



