IONIC AND OSMOTIC CONDITIONS 



63 



0.5 1.0 1.5 20 2.5 3.0 3.5 



HOURS 



Fig. 1. Effect of $ reproductive tract fluids on aerobic metabolism of 

 bull sperm. Number of sperm samples, n, equals 2 (Olds and VanDemark, 

 1957a). 



figure shows clearly that while metabolic activity is depressed by the 

 secretions found in the vagina, cervix, and uterus, it is markedly 

 stimulated by those of the oviducts and follicular fluid. 



OSMOTIC PRESSURE AND CATION CONTENT OF FLUIDS FROM MALE 

 AND FEMALE REPRODUCTIVE TRACTS 



The osmotic balance and ionic concentration of the primary cat- 

 ions in epidiclymal fluid (Salisbury and Cragle, 1956), semen (Cragle 

 et al., 1958a, b; Rothschild and Barnes, 1954a, b; Salisbury et al., 

 1948), and the female reproductive tract fluids (Olds and VanDe- 

 mark, 1957) are shown in Table II. 



Note that the freezing point depression for fluids of the epi- 

 didymis (Salisbury and Cragle, 1956) is greater than is that of semen 

 (including the spermatozoa) (Salisbury et al., 1948) and that of semi- 

 nal plasma (Rothschild and Barnes, 1954a). These values are equiva- 

 lent to a concentration of particles exerting osmotic pressure of about 

 350-360 milliosmoles in the epididymis, and as low as 285 millios- 

 moles in seminal plasma. These data, in conjunction with other meta- 

 bolic data presented later, indicate that one natural means of re- 

 ducing the metabolic activity of spermatozoa in the epididymis may 

 be its high milliosmole concentration of particles. 



