Fertilizing capacity of various populations of spermatozoa within an ejaculate.

To determine whether ejaculates consist of various populations of sperm with varying degrees of fertilizing capacity, semen was filtered through a glass-wool column and the filtrate aliquoted sequentially into three portions. The ejaculate and its respective filtrates were evaluated for progressive motility, ability to respond to hypoosmotic swelling (HOS) test, acrosin content, ability to capacitate and acrosome react (AR), and ability to penetrate into denuded hamster oocytes (SPA). Filtrate 1 contained significantly more sperm with progressive motility, increased acrosin content, and positive HOS and SPA results than did the ejaculate. AR did not differ between the ejaculates and the respective filtrates. The data suggest that the ejaculate consists of various populations of sperm with different properties and that these populations may be separated by glass-wool filtration.