FIG. 4.

Sperm capacitation and acrosome reaction in Cst8^+/+ and Cst8^−/− mice. A) Spermatozoa from Cst8^+/+ (filled circles) and Cst8^−/− (filled squares) mice after various times of capacitation were induced to undergo the acrosome reaction by the calcium ionophore A23187 (left) or progesterone (right). Spermatozoa from Cst8^+/+ (open circles) and Cst8^−/− mice (open squares) that were incubated in DMSO vehicle only and, thus, represent spontaneous acrosome reactions are also shown. The present or absence of the acrosome was determined by Coomassie Blue staining. Values represent the mean ± SEM (A23187, n = 3; progesterone, n = 4). An asterisk indicates statistical significant (*P ≤ 0.001) comparing Cst8^+/+ to Cst8^−/− spermatozoa in the presence of progesterone. B) Western blot analysis of protein tyrosine phosphorylation in Cst8^+/+ and Cst8^−/− spermatozoa after increasing periods of time in capacitation buffer. The blot is representative of that from three different sperm capacitation experiments. Coomassie Blue staining of the blot confirmed equal loading of protein in each lane (not shown).