A carbohydrate-based mechanism of species recognition in sea urchin fertilization. P.A.S. Mourão. Braz J Med Biol Res 2007; 40: 5-17.   

Figure 3. Structure and effect of sulfated polysaccharides from the sea urchin egg jelly as inducers of the acrosome reaction in sperm of three species that co-exist in the sea harbor of Rio de Janeiro, Brazil. Data modified from Alves et al. (39) (printed with permission).