Vegetalization Induced by Procaine and Tetracaine in Sea Urchin Embryos

Vegetalization of sea urchin embryos was induced by the treatment with procaine and tetracaine, inhibitors of Ca²⁺mobilization, for 3 hr starting 3–5 hr after insemination at 20°C. The treatment starting 7 hr after insemination sometimes produced similar type of vegetalized embryos. The pulse treatment starting at the other stages hardly yielded vegetalized embryos. The stages at which these compounds were effective to produce vegetalized embryos were almost the same to those for Li⁺to make embryos vegetalized. On the basis of known inhibitory effects of tetracaine, procaine and Li⁺on Ca²⁺mobilization, we postulate that Ca²⁺dependent reactions participate in the process of cell determination at these stages. Inhibitory effects of procaine, tetracaine and Li⁺on Ca²⁺dependent induction of fertilization membrane formation, found in the present study, indicate that these compounds block Ca²⁺mobilization in sea urchin eggs.