The Study Of The Fertilization Cytology And The Early Embryonic Development Of The Red Crucian Carp (carassius Auratus Red Var.)(♀)×megalobrama Amblycephala(♂)

The tetraploid and triploid hybrids have been found in the offspring of cross the red crucian carp (Carassius auratus red var.) (RCC) (♀)×Megalobrama amblycephala (BSB) (♂). In the present study, the fertilization cytology and the early embryonic development of the hybrids were described.The study on the hybrid of the RCC(♀)×BSB(♂) was conducted. At 18~21℃of the water temperature, the spermaster was obviously appeared and the elimination of the second polar body was extruded at 7 minutes after fertilization. By the 15 minutes post insemination, the male and female pronuclei were found, and subsequently, they moved toward the center of blastodisc, then contacted with each other; lastly fused completely to be the zygotic nucleus. The first cleavage occurred at about 35 minutes after fertilization, and then the cleavage occurred every 15 minutes. Noticeably, some eggs fertilized were found at the stage of the first cleavage indicated that they developed slower obviously than other eggs which had reached the first cleavage at 40 min after fertilization. It is suggested that those kind of eggs was inhibited, which probably resulted in the formation of the allotetraploid hybrid of the RCC(♀)×BSB(♂).Furthermore, at the water temperature of 18～21℃, the fertilized eggs began the first cleavage 40 min after fertilization and reach morula stage (2h25min), blastula stage (3h15min), gastrula stage (6h15min), neural stage (10h15min), organogenetic stage (14h); And were hatched out 54.5～60 hours after fertilization. The results indicated that the embryonic cells had normal behavior during the early embryonic development.