BLOCKING OF HUMAN FERTILIZATION BY CARBOHYDRATES

The zona penetration test and triple stain technique were used to eluc idate the blocking effects of carbohydrates on human fertilization and their mechanisms. In the presence of D-mannose or D-fructose (final c oncentration, 50 mmol/l), sperm penetration through the human zona pel lucida was completely blocked. The triple stain technique revealed tha t D-fructose (50 mmol/l) significantly (P < 0.01) suppressed the acros ome reaction of human spermatozoa, while D-mannose did not show a supp ressive effect on the acrosome reaction. These results reinforce our h ypothesis proposed previously, that a mandatory step in human fertiliz ation is the binding of a D-mannose-binding constituent of the sperm s urface to a D-mannose residue in the sperm receptor site on the zona p ellucida. In addition, D-fructose may play an important role as an acr osome stabilizing factor in seminal fluid.