Fig. 1. Ovulated, but not ovarian, zona pellucida (ZP) glycoproteins contain a ligand that competitively inhibits GalT I-null sperm binding to ovulated eggs. (A) Inhibition of wild-type and GalT I-null sperm binding to ovulated eggs with 0-75 ng/µl solubilized ovarian ZP. (B) Inhibition of wild-type and GalT I-null binding with 0-5 zonae equivalents solubilized ovulated ZP. Each point represents the mean±s.e.m.; n=3 experiments. In a single experiment, the value for each data point represents the average of three determinations (for a total of nine assays per data point).