Fig. 5. GalT I-null sperm do not require albumin, Ca²⁺, or HCO₃^– during capacitation to undergo an ionophore-induced acrosome reaction. Wild-type (gt +/+) and GalT I-null (gt –/–) sperm were capacitated for varying periods of time in complete media (unbroken line) or in media lacking (broken line)either albumin (A), Ca²⁺ (B) or HCO₃^– (C). Sperm were subsequently incubated with 10 µM A23187 and the appropriate co-factor (to reconstitute complete media) and the percentage of acrosome-reacted sperm was determined. Each point represents the mean±s.e.m.; n=3 experiments. In a single experiment, the value of each data point represents three determinations for a total of nine assays. A minimum of 200 sperm was counted for each of the assays.