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 DI and causes a rapid depolarization. A high incidence of polyspermy (36 %) was detected by in vivo observations of fertilization cone formation. Polyspermie 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 mem-brane potential. The role of the egg envelopes in regulating sperm–egg interaction is discussed.

Keywords:
polyspermy, anuran, membrane potential, Discoglossus pictus
© 1989 by Company of Biologists
1989
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