Induction of the acrosome reaction in ejaculated goat and boar spermatozoa by preincubation in isolatd rat uterus and elucidation of possible inducing factor(s).

Washed ejaculated goat and boar spermatozoa were preincubated in isolatedrat uteri, open test tubes and sealed glass tubes with or without rat uterine fluid. The acrosome reaction was evaluated by a triple-stain technique and a hamster test. Goat and boar spermatozoa underwent the acrosome reaction during preincubation in the isolated rat uteri and sealed tubes. In the open test tubes, the acrosome reaction did not occur in the goat, but did in the boar. The addition of rat uterine fluid to the medium accelerated the onset of the acrosome reaction in goat spermatozoa preincubated in sealed tubes and in boar spermatozoa in open test tubes. Increasing sperm concentration in the suspension promoted the acrosome reaction. These results indicated that the acrosome reaction of boar spermatozoa could be induced by preincubation in open test tubes, and preincubation in isolated rat uteri and sealed tubes was effective for inducing the acrosome reaction of both goat and boar spermatozoa, and that the supplemented rat uterine fluid in the medium shortened the time required for inducing the acrosome reaction. Possibly, the difference in the effect of preincubation in open test tubes between these two species may correspond to the difference in the mechanism to acquire energy between them, and one of the factors in isolated rat uteri to induce the reaction may be a lack of oxygen.