The Two Components of Semen 25 



To a considerable extent, however, the activation by seminal plasma 

 has been shown to be linked with the occurrence of specific sub- 

 stances in the different accessory gland secretions. In certain insects, 

 Bombyx mori for example, the spermatozoa are believed to acquire 

 their full fertilizing capacity only after activation by the secretion 

 of the lower portion of the male tract, the so-called glandula pros- 

 tatica (Wigglesworth, 1950). Many investigators have studied the 

 activating influence of the prostatic secretion on mammalian sper- 

 matozoa (Steinach, 1894; Hirokawa, 1909; Ivanov, 1929; Sergijewski 

 and Bachromejew, 1930), and in some instances, e.g. the dog, have 

 claimed it to be species-specific (Ivanov and Kassavina, 1946), By 

 no means all of these experiments, however, have been carried out 

 under satisfactorily controlled conditions and, as Huggins (1945) 

 thinks, in many cases it is impossible to exclude the action of non- 

 specific factors such as acceleration of sperm motility by certain ions 

 or by changes in the gas tension. 



Much discrimination is equally needed in appraising certain 

 results obtained with the epididymal secretion. Here, however, the 

 problem involves not so much the 'activation', as the 'ripening' and 

 'life-prolonging', effects on the spermatozoa (Tournade and Mer- 

 land, 1913; Stigler, 1918; Braus and Redenz, 1924; Hammond and 

 Asdell, 1926; Young, 1929, 1930; Young and Simeone, 1930; Lanz, 

 1931, 1936; Gunn, 1936; Gunn, Sanders and Granger, 1942). Most 

 investigators agree that in some special way the epididymis is 

 adapted for the long-term storage of spermatozoa; but whereas some 

 like Braus and Redenz (1924), attribute to the epididymal secretion 

 a specific role in the 'ripening' process, others deny it such a func- 

 tion. In the seminal vesicle fluid, we seem to be confronted with an 

 activating effect on spermatozoa different from that exerted by the 

 prostatic and epididymal secretions, one which is specifically bound 

 up with the presence therein of fructose which provides a source of 

 nutrient material for the sperm cells. 



Another facet of the physiological function of the seminal plasma 

 concerns certain characteristic pharmacological effects of the acces- 

 sory gland secretions and the role of seminal plasma in the remark- 

 able process of semen coagulation and liquefaction. 



