Cold Shock Compromises the Electrically Mediated Block to Polyspermy in Lytechinus variegatus Eggs

Exposure to low temperature prior to insemination increases the likelihood of polyspermy in Lytechinus variegatus eggs. Electrophysiological recordings reveal that cold shock partially disrupts the egg's action potential, producing a subthreshold depolarization during the fertilization response. This attenuated shift in membrane potential appears insufficient to activate the fast block to polyspermy, allowing entry of multiple sperm. These findings identify a temperature-sensitive vulnerability in the electrical barrier to polyspermy in sea urchin eggs.