Fertilization in Discoglossus pictus (Anura)

摘要: The heterogeneity of the egg surface with respect to receptivity sperm was investigated in Discoglossus pictus; this species fertilization occurs only an indentation called dimple, at center animal hemisphere. Following insemination are seen outermost jelly layers and lens-shaped plug, converging dimple center, D1. A potential (FP) is recorded 30 sec following insemination. About min after fertilization, when cones can be detected easily, immotile found cone, where 10 later they accomplish penetration. After 15 cone regresses second polar body extruded. In eggs plug experimentally displaced spermatozoa contacted sides simple protrusions formed but not cones. Spermatozoa do elicit a normal FP these regions small step depolarizations which may followed by gradual rise positive plateau potential. Such develop. protrusions, partially incorporated unpenetrated portion appears degenerate. We conclude that least two exist dimple: D1, triggered, formed, penetration fully accomplished development initiated; D2 + D3 electrical response FP, form, total does occur, initiated.