Polyspermic eggs in the anuran Discoglossus pictus develop normally

Fertilization and development in 400 eggs of the anuran Discoglossus pictus has been followed. In these eggs successful sperm interaction is restricted to a small area of the animal dimple called D1 and causes a rapid depolarization. A high incidence of polyspermy (36%) was detected by in vivo observations of fertilization cone formation. Polyspermic eggs gave rise to fertilization potentials comparable to monospermic eggs and developed normally. By using current-injection technique it is shown that sperm penetration is independent of membrane potential. The role of the egg envelopes in regulating sperm-egg interaction is discussed.