The cytological behavior of sperm was observed after the sperm incorporated into dechorioned eggs of gynogenetic Silver crucian carp (Carassius gibelio) and bisexual fish (Carassius auratus red variety or Cy prinus carpio red variety). In bisexual dechorioned eggs the sperm nuclei may undergo decondensing and developed into pronuclei. By contrast, although a few heterologous sperm nuclei became to some extent enlarged the pronuclei did not appear all. Furthermore, the established cell-free system from extraction of two types of eggs were employed to incubate the Triton-X100 treated sperm. The sperm nuclei in the two types of extractions were fully developed, and then became the form of pronucleus, indicating that there are some factors responsible for sperm nucleus swelling and male pronucleus formation in gynogenetic Silver crucian carp eggs. However, when heterologous sperm entered intact gynogenetic eggs through micropyle, the nuclear envelope of sperm failed to breakdown due to the abnormality of relative function in cytoplasm of the egg, and the further development was thus inhibited. The significance of setting-up cell free system ties in that an efficient approach can be established to analyse the molecular mechanism by which the natural gynogenesis was regulated during fertilization.