In vitro fertilization and the effect of progesterone and 17 alpha-hydroxyprogesterone on acrosome reaction of mouse epididymal spermatozoa.

This study assessed the effect of progesterone and 17 alpha-hydroxyprogesterone (17 alpha-OH-progesterone) at concentrations of 0.01-10 micrograms/ml, on the acrosome reaction and in vitro fertilizing ability of mouse epididymal spermatozoa. Cumulus masses containing oocytes were cultured in Brinster's medium, to which were added capacitated epididymal spermatozoa which had been incubated in medium with various concentrations of progesterone or 17 alpha-OH-progesterone for 90 min. IVF success rate was assessed 20-24 h following insemination. Progesterone was found to increase the fertilization rate at the 1 microgram/ml and 10 microgram/ml concentrations while lower concentrations had no effect. However, 17 alpha-OH-progesterone failed to show any effect on fertilizing ability. Incubation of epididymal spermatozoa in medium containing 1 microgram/ml and 10 micrograms/ml progesterone significantly increased the acrosome reaction as monitored by a chlortetracycline fluorescence assay. 17 alpha-OH-progesterone, however, failed to show any effect on the acrosome reaction. The results suggest direct effects of progesterone, but not of 17 alpha-OH-progesterone, on fertilization and the acrosome reaction of mouse spermatozoa.