On the Fertilization of the Triploid Ginbuna
摘要
The ferilization process of the gynogenetic triploid ginbuna Carassius auratus langsdorfii were observed histologically. In the triploid female, it has been reported that the sperm nucleus remains in condensed condition throughout the ferilization to first cleavage. This sperm nucleus does not fuse with female pronucleus, producing the all female triploid offsprings gynogenetically. On the other hand, in the present experiment, in some triploid eggs, the penetrated sperm nucleus swells to form male pronucleus. Some of these eggs develop into tetraploid other than triploid fish. On the scale transplantation experiments between these offsprings, in which all of the sperm nuclei had swollen at the time of fertilization, the unidirectional rejection were observed in two combinations. One of these donors was tetraploid and other was triploid. It seems probable that the former unidirectional rejection might be caused by the introduction of paternal genome, and the later might be caused by the recombination of genes at meiosis or the mutation of the donor and/or the host. From these observation, it was ascertained that the offsprings of triploid ginbuna were not always belonging to the same clone but that some of them differenciated their genome during the gametogenesis or early developmental stage.