Abstract: | The effect of trypsin on the fertilizing capacity of spermatozoa was studied with 6 species of sea urchins. Trypsin has no harmful effect on intact spermatozoa. However, spermatozoa which have undergone the acrosome reaction in egg-water lose the fertilizing capacity when treated with trypsin-sea water. Electron- microscopical examination revealed that trypsin does not produce any morphologically noticeable effect on intact spermatozoa, but does dissolve the material covering the acrosomal tubule of the spermatozoa which have undergone the acrosome reaction. It is likely that the loss of this material is closely correlated with the loss of fertilizing capacity of spermatozoa by the trypsin treatment. |