Evidence suggesting that L‐fucose is part of a recognition signal for sperm‐zona pellucida attachment in mammals

Experiments were designed to test the effects of simple sugars and complex polysaccharides on the attachment of mammalian spermatozoa with the zona pellucida. In the guinea pig, L-fucose was a twofold better inhibitor of the attachment compared to other sugars at 50 mM. Fucoidin, an algal polysaccharide rich in sulfated L-fucose, was a very potent inhibitor, completely blocking attachment at a concentration of 100 μg/ml. Several other highly sulfated glycosaminoglycans showed no inhibitory activity, suggesting the fucoidin effect was not simply due to its charge or sulfate. In addition, fragments of fucoidin, generated by partial hydrolysis and isolated using Biogel P-2, were nearly as inhibitory as the native molecule on a weight basis. Fucoidin also inhibited sperm-zona attachment in the hamster and human; thus, its effect is not species specific. The data suggest that L-fucose may be part of a recognition signal between mammalian gametes.