Antagonistic and agonistic properties of saccharide moieties in the hemizona assay.

The hemizona assay (HZA) was used to evaluate the effects of different sugars on human sperm-zona pellucida interactions. In each controlled assay, sperm binding from men of known fertility with/without preincubation with different carbohydrate constituents was compared. We used human prophase I oocytes obtained from surgically removed ovaries; these oocytes were stored in salt solution and later bisected by micromanipulation. Preincubation of sperm (1 hour) with fucoidin (1.0 mg/mL) significantly inhibited binding by more than 85% as compared with controls. Similarly, lesser fucoidin concentrations of 0.5, 0.25, and 0.01 mg/mL were markedly inhibitory. In addition, preincubation times of 60, 30, and 15 minutes were not different in their degree of inhibitory effect. On the other hand, preincubation of the hemizonae with fucoidin before HZA inhibited binding by 43% compared with controls. Here, the fucoidin effect was significantly less inhibitory than the sperm preincubation effect of fucoidin. Preincubation of sperm with d-fucose had no measurable effect on binding, whereas d-glucose (1.0 mg/mL) and 1-fucose (1.0 mg/mL) increased binding. These results indicate: (1) that the HZA provides a unique internally controlled homologous bioassay to evaluate the effects of simple and complex carbohydrates on sperm zona interactions; (2) that fucoidin is an immediate (less than 15 minutes) inhibitor of human sperm binding to the human zona pellucida under HZA conditions.