STUDIES ON THE PHENOMENA OF STIMULATING THE DEVELOPMENT OF SPERM NUCLEUS DURING OOCYTE MATURATION IN TWO TYPES OF FISHES

Using the experimental cytological methods, we studied the development of the injected red carp (Cyprinus carpio red variety) sperm nuclei in the oocytes at different stages of maturation in the amphimictic fishes [red carp and colored goldfish (Carassius auratus colored variety)] and the gynogenetic crucian carp (Carassius auratus gibelio). The results showed that, in the oocytes of amphimictic and gynogeneic fishes, the decondensation of injected sperm nuclei began at the same time (GVBD), but their pronucleation started at the later metaphase of the meiosis I and the later phase of the formation of the tripolar spindle respectively. In oocytes of the gynogenetic crucian carp, the decondensed degree of the sperm nuclei was same as those in the amphimictic fishes, but their pronucleated degree was much lower. Based on those results, we concluded that, during the oocyte maturation in red carp and colored goldfish, two types of factors could be produced successfully. One type controls the decondensation of sperm nucleus (termed sperm nucleus decondensation factors: SNDFs), while the other controls pronucleation (termed sperm pronucleus developmental factors: SPDFs). During the oocyte maturation in the gynogenetic crucian carp, the activities of the SNDFs were the same as those in the amphimictic fishes, but the activities of SPDFs were very low. The expression of the activitis of SNDFs in the ova of both amphimictic and gynogenetic fishes is related to the GV materials, but the expression of the activities of SPDFs is different between two types of fishes. The activities of SPDFs appear to bear an important relationship to the normal completion of meiosis I. The gynogenetic crucian carps, which have the abnormal meiosis I, show reduced activities of SPDFs.