The gamete membrane fusion test to assay the fertilizing ability of human spermatozoa*

The value of the gamete fusion test for the assessment of human spermatozoa is assessed. The factors influencing the test are discussed, including the conditions of heterologous fertilization using zona-free oocytes such as the nature of sperm preparation, sperm concentration and capacitation time, and the importance of albumin in the medium. The oocytes can be examined before or after fixation, and the spermatozoa around the eggs assessed for acrosome changes, while the number of sperm tails on the oocyte can be related to the number of chromatin decondensations. The test provides information on the fertilizing ability of spermatozoa of given individuals, and may prove of value in testing contraceptives.