A cytological study on gynogenesis of Chuzhou Crucian carp(Carassius auratus)

The purpose of our investigation was to examine whether the Chuzhou Crucian carp caught from City-west reservoir in Chuzhou City,Anhui Province,would reproduce by gynogenesis.Their spawns were artificially inseminated with milt of Crucian carp and Red carp(Cyprinus carpio L.red variety),and a number of fertilized eggs were studied cytologically before their first cleavages.The results of observation are as follows:(1) No polar body was found in the ripe egg cells just after spawning.About 15 minutes after insemination(at 18～20℃ water),a single polar body was extruded.(2) In the fertilized eggs,the sperm nucleus remained as a condensed mass and did not transform into male pronucleus.(3) After the single polar body was extruded,about 20 minutes after insemination,the eggs nucleus transformed into female pronucleus,but before their first cleavages no amphimixis was observed.(4) The heterologous sperm could normally enter the egg cytoplasm of Chuzhou Crucian carp and activate female pronucleus formation and normal development into embryos.The results showed that either homologous or hoteroloous sperm nucleus had the same developmental process.The fry developed normally and no deformed fry and hybridization features were found.As above,the results of the present observation indicated that the Chuzhou Crucian carp did reproduce by gynogenesis.