Production of motile acrosome-reacted mouse sperm with nanomolar concentration of calcium ionophore A23187.

A method to generate a population of motile, acrosome-reacted mouse sperm is described. Sperm retrieved from the cauda epididymis and vas deferens were first capacitated in a 3% bovine serum albumin (BSA) containing medium. Sperm were then resuspended in medium with low BSA content (0.01%) and treated with 30 nM of the calcium ionophore, A23187, which was added as a single dose of 30 nM for 15 min at 37 degrees C; or three sequential 10 nM doses over three 5 min intervals. Approximately 55-60% of the treated sperm population became acrosome reacted. The motility of the treated sperm sample was 40-65%, slightly lower than that of the control sperm, following addition of medium containing 3% BSA. This is in contrast to the < 10% motility observed for capacitated mouse sperm treated with 10 microM 23187, a concentration that had been used by other investigators to induce the acrosome reaction. The ultrastructure of the 30 nM A23187-induced acrosome-reacted sperm was similar to that of the acrosome-reacted sperm induced by solubilized zonae pellucidae. These motile, acrosome-reacted sperm were able to penetrate zona-free mouse eggs at a higher rate than the control sperm. Thus this method of treatment will be useful for further physiological experimentation with acrosome-reacted sperm.