electrical polyspermy block

Jaffe, LA, Gould-Somero M, Holland LZ.  1979.  Ionic Mechanism of the Fertilization Potential of the Marine Worm, Urechis caupo (Echiura) . Journal of General Physiology . 73(4):469-492.
Holland, LZ, Gould-Somero M.  1981.  Electro-physiological response to insemination in oocytes of Urechis caupo. Developmental Biology. 83(1):90-100.