关键词: 大竹蛏(Solen grandis Dunker), 精子, 精子发生, 超微结构

Abstract:

The ultrastructure of spermatogenesis and spermatozoon of Solen grandis was observed by transmission electronic microscope. The results showed ultrastructural changes from spermatogonium to spermatozoa. The spermatogenesis of Solen grandis included five stages: spermatogonium, spermatocyteⅠ, spermatocyteⅡ, spermatid and spermatozoon. The spermatozoon, of a typical primitive type (52—57 μm), consisted of a head, a middle piece and a tail. The head comprised of a bowl-shaped acrosome and a warhead-shaped nuclear. Four or five ellipsoidal mitochondria and two centrioles made up the middle piece. The tail was thin but long, with a typical structure as type “9+2.” The distinctions of spermatogenesis and sperm morphology between Solen grandis and Solen strictus were also discussed. High-density material lying at the circumference of a proacrosomal vesicle was arched with a gap in Solen grandis, but round in Solen strictus. From this gap a proacrosomal vesicle of Solen grandis began to invaginate and deform while it moved to the nuclear front. However a proacrosomal vesicle of Solen strictus did not deform until it reached the nuclear front. Solen grandis was longer than Solen strictus. The nuclear of Solen grandis was warhead-shaped while one of Solen strictus’s was spherical. A satellite body was found in Solen grandis but not in Solen strictus. In addition, Solen grandis had a longer tail than Solen strictus. The results can provide reference for identification and genetic relationship analysis of Solenidae.

Key words: Solen grandis, spermatozoon, spermatogenesis, ultrastructure