Indirect Assement of Sperm Capacitation Using Zona-free Hamster Eggs in the Goat II. Penetration into Zona-free Hamster Eggs by Goat Spermatozoa Preincubated in a Chemically Defined Medium

Ejaculated and epidiymal goat spermatozoa were preserved for 0, 6, 12 adn 18 h, and 0 and 18 h in a semi-aerobic condition at 20-$25^{\circ}C$, and preincubated for 5-6 h in a CO2 incubator in m-KRB solution. Then they were preincubated at different concentrations (3-5, 25-48 and 105-190$\times$107/ml), and ability of penetration into zona-free hamster eggs in vitro was examined. When ejaculated spermatozoa were preincubated in m-KRB solution after presservation for 12 and 18 h, 12 and 29% of zona-free eggs were penetrated, and only 4% of eggs were penetrated by epididymal spermatozoa which were preincubated after preservation for 18 h. When spermatozoa were preincubated at a low concentration, the penetration rates were very low. But when the sperm concentration during preincubation was 25-48 and 105-190$\times$107/ml, the penetration rates increased to about 30%.