STUDY ON FERTILIZATION CYTOLOGY ANDEMBRYONICDEVELOPMENT IN HYBRIDIZATION BETWEEN OREOCHROMIS AUREA (♀) AND SINIPERCA CHUATSI (♂)

Tilapia are native to Africa, but have been introduced into many countries around the world.They are disease-resis-tant, reproduce easily, eat a wide variety of foods and tolerate poor water quality with low dissolved oxygen levels, but are not able to bear low temperature.Mandarin fish, a carnivore freshwater fish,is popular with the advantage of rich nutrition and deli-cious tasty. So we want to obtain a new breed through hybridization between Oreochromis aurea(♀) and Siniperca chuatsi(♂). And we finally got some progenies through this experiment. The insemination biology in hybridization between O. aurea(♀)and S.chuatsi(♂)reveals that the sperm of S.chuatsi can enter the egg cytoplasm of O. aurea, then grow into spermaster and finally form the male pronucleus.After a while, the fe-male and male pronucleus contact and fuse each other, and ultimately became zygote nucleus.Observing the embryonic development between the hybrid and its parents (O. aurea and S.chuatsi), we discover that the embryonic development rate of the hybrid is much closer in the early-blastula and is little slower in the late-blastula to that of O. aurea, but is considerably differentto that of S. chuatsi.Although the hybridization between O. aurea(♀)and S. chuatsi(♂)is distant hybridization, this study shows that the whole process obeys the normal fertilization process and cleavage.