THE EFFECT OF SOLUBLE EGG JELLY ON THE FERTILIZABILITY OF ACID-DEJELLIED SEA URCHIN EGGS*

Abstract

Acid-dejellied Lytechinus pictus eggs bind few sperm and show decreased fertilizability. Addition of solubilized egg jelly increases sperm binding and fertilizability, presumably by increasing the frequency of the acrosome reaction. Dejellied Strongylocentrotus purpuratus bind more sperm and show increased fertilizability in the complete absence of soluble egg jelly. Addition of soluble egg jelly greatly decreases fertilizability in S. purpuratus. Such species differences may be the basis foC the controversy between Lillie and Tyler who believed that egg jelly increased egg fertilizability and Loeb and Hagstrom who belived jelly had no effect on or actually decreased egg fertilizability. 125I-labeling of dejellied S. purpuratus egg surfaces and immunofluorescent studies show that egg jelly persists on the surfaces of acid-dejellied eggs. Egg jelly appears a non-removable component of the vitelline layer of this species.