CHAPTER II 



Chemical and Physical Properties 

 of Whole Ejaculated Semen 



Species and individual variations in the composition of semen. Pre- 

 sperm, sperm-containing, and post-sperm fractions in the ejaculate. 

 Criteria for the rating of semen quality. Optical and electrical properties 

 of semen. Viscosity, specific gravity, osmotic pressure, and ionic equi- 

 librium. Hydrogen ion concentration and buffering capacity. Metabohsm 

 of semen and its relation to sperm density and motility; glycolysis; 

 methylene-blue reduction test; respiration. 



Species and individual variations in the composition of semen 

 A CHARACTERISTIC feature of whole semen is the variability of its 

 composition not only among different species but also between in- 

 dividuals of the same species (Table 4). Somewhat less pronounced 

 but still significant are the variations in the concentration of some 

 of the semen constituents in the same individual (Table 5). All this 

 is not altogether unexpected since both the spermatogenic activity 

 of the testes and the secretory function of the male accessory organs 

 are subject to considerable physiological fluctuations of hormonal 

 origin and are influenced by factors such as light, temperature, 

 season, state of nutrition etc. The variability of semen composition 

 is the reason why repeated examination of whole semen, even if 

 restricted to a single experimental subject, and carried out under 

 identical experimental conditions, need not yield the same quanti- 

 tative results, as might, for example, an analogous series of blood 

 analyses in the same individual. Therefore, an accurate estimate of 

 semen quality in any one individual cannot be formed on the basis 

 of a single analysis and involves several examinations. 



In Table 5 are shown individual fructose variations in the semen 

 of man, bull, ram and rabbit. The analytical results are given in 

 terms of concentration (mg./lOO ml. semen) and of absolute content 



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