The effect of sperm concentrations during preincubation and at insemination on fertilization of rat eggs in vitro

This is the authors' abstract. We don't add key points for this paper.

Rat epididymal spermatozoa, at a concentration of 40-65 X 10(4) cells/ml, were preincubated for 5-5, 5 hr and then added to eggs from superovulated, immature rats. By 10-12 hr after insemination, 86% of the eggs had undergone fertilization, but many of them (41%) were polyspermic. When sperm were preincubated at almost the same concentration and for the time stated above, but then diluted to 1-3 X 10(4) cells/ml before insemination, the number of fertilized eggs and the incidence of polyspermy were both reduced, being 56% and 5%, respectively. When a sperm concentration of 1-3 X 10(4) cells/ml was used both during preincubation and at insemination, the fertilization rate of 60% or more, with polyspermy not in excess of 10%, a sperm concentration of 30-100 X 10(4) cells/ml during preincubation and then diluted to approximately 1-3 X 10(4) cells/ml at insemination appears to be optimal.