The Factor in Egg Yolk Affecting the Resistance, Storage Potentialities, and Fertilizing Capacity of Mammalian Spermatozoa

The division of spermatozoan resistance into two distinct types has been suggested and the relationship of each to problems of reproductive physiology has been discussed. The procedure has been presented for the isolation of an active resistance factor from egg yolk which gives a water-clear solution in phosphate buffer and which has proved more effective than the original egg yolk-buffer mixture in increasing the resistance of spermatozoa to adverse conditions. It has been shown that the increased effectiveness may be the result of the removal of an alcohol-soluble fraction which is detrimental to spermatozoan viability. Some of the chemical characteristics of the active fraction of egg yolk have been described. It may be that the active factor in this fraction possesses similar characteristics. Further, identification of the factor present in the active fraction and knowledge of the mechanism whereby it influences spermatozoan resistance should aid, it has been suggested, in the solution of some of the problems of reproductive physiology as well as making a definite contribution to our knowledge of general cellular physiology.