THE TOXICITY OF VARIOUS NON-ELECTROLYTES TO HUMAN SPERMATOZOA AND THEIR PROTECTIVE EFFECTS DURING FREEZING

Abstract
At concentrations varying from 2.5% to 10.0%, glycerol, dimethyl sulphoxide, ethylene glycol, methyl formamide and methyl acetamide had approximately equally toxic effects on human spermatozoa; whereas dimethyl formamide and dimethyl acetamide were considerably more toxic at the same concentrations. Glycerol and ethylene glycol afforded an equal protective action to human spermatozoa during freezing and thawing, approximately 50% of the original motility being retained, but negligible protection was exhibited by methyl formamide, dimethyl formamide, methyl acetamide and dimethyl acetamide. Only 34% of the original motility was retained when human spermatozoa were frozen in the diluent containing dimethyl sulphoxide.