Ultrastructural Localization of Calcium in the Acrosome and Jelly Coat of Starfish Gametes

The potassium pyroantimonate technique was employed to localize calcium ultrastructurally on both male and female starfish gamete regions that first interact at fertilization. In the spermatozoon of Marthasterias glacialis , antimonate precipitates in the peripheral dense component of the acrosomal vesicle, while in the oocyte it precipitates in the jelly coat and beneath the oolemma. Calcium was identified in the precipitates by testing the chelator-sensitivity and by X-ray microanalysis of the precipitates.