IONIC AND OSMOTIC CONDITIONS 61 



determine the effect of naturally occurring inhibitors and stimu- 

 lators of spermatozoan metabolic rate have been done in Warburg 

 respirometers under air, with the fructose of semen (or fructose 

 added to washed cells) as the substrate. However, replacement of air 

 by nitrogen is one form of metabolic control. Thus, to obtain ul- 

 timate control we have used anaerobic conditions, also. 



MODEL CONDITIONS REPLICATED 



In assaying the osmotic and ionic requirements for motility of 

 spermatozoa the author and his colleagues have considered the fol- 

 lowing model conditions with bovine spermatozoa: (1) in the epi- 

 didymis, where motility and metabolic activity are minimized by 

 lack of substrate, by the balance of cations and anions, and by low 

 gaseous exchange; (2) in semen itself where carbohydrate substrate 

 is plentiful, a change has occurred in the ion balance on ejacula- 

 tion and the metabolism and motility proceed at intermediate rates 

 under anaerobic conditions but are optimum in the presence of oxy- 

 gen; and (3) in the presence of the stimulatory secretions of the fe- 

 male upper reproductive tract. 



It has not been possible to perform the experiments in situ. How- 

 ever, recourse has been made to replication of the media and sub- 

 strate situation found in the various parts of the male and female 

 reproductive tracts in so far as current knowledge permitted. We 

 have made use of sperm cells in diluted semen, of washed ejaculated 

 sperm cells, and more recently, of specially collected epididymal- 

 like washed spermatozoa. Measurements were made of metabolic 

 activity in the Warburg apparatus by gaseous exchange and by di- 

 rect chemical analyses. Some interesting observations have been made 

 relative to the control of spermatozoan metabolism and of motility 

 by the conditions employed in these experiments, which are be- 

 lieved to be replication of those found in nature. The primary re- 

 sults will be reviewed here. 



RATES OF AEROBIC METABOLISM BY BULL SPERMATOZOA 



Table I shows the comparative means and standard deviations of 

 biochemical activity found for bull spermatozoa of different types 

 and for the several conditions tested. The Z (for Zelle) values (mi- 



