In this dissertation, the differentially expressed genes in fully grown oocytes between gynogenetic silver crucian carp (Carassius auratus gibelio) (gyno-carp) and gonochoristic crucian carp (Carassius auratus color variety) (gono-carp) were compared using subtractive hybridization method. Four differentially expressed full-length cDNAs have been cloned and their characterizations have been analyzed. The first one is the unknown gene CB102 whose transcripts are more abundant in fully grown oocyte of gono-carp. Sequence predication shows that it may be a transmembrane protein. It is an ovary specific gene and is expressed in all stages of oogenesis. In early embryogenesis, CB102 is expressed at high level from fertilization to morula stage. After that, its expression decreases and its mRNA can not be detected after hatching embryo stage. The second one is the novel gene YA2 that is specifically expressed in fully grown oocyte of gyno-carp and encodes a short peptide of 66aa. Its expression remains at high level from fertilization to neurula stage and decreases after tail bud stage, and its mRNA can not be detected after larvae stage. The third one is histone H2A. The sequences of histone H2A of the gyno-carp and gono-carp are quite different at C-terminal. The fourth gene is cyclin A2 whose full-length cDNA is reported in fish for the first time. Comparing the three cyclins' sequence differences between gyno-carp and gono-carp demonstrates that the amino acid sequences of cyclin A2 are more variable than cyclins A1 and B, and 3' untranslated region sequences of cyclins A2 and B are more variable than cyclin A1. In fully grown oocyte of gyno-carp, cyclin A2 mRNA is more than 20 folds, and cyclin A1 mRNA is about 2 folds comparing to that of gono-carp. However, cyclin B does not have such a difference. Western blotting analysis also demonstrates that a large amount of cyclin A2 proteins are stockpiled in fully grown oocyte of gyno-carp, while the protein is under the detectable level in fully grown oocytes of gonochoristic color crucian carp, red carp and mirror carp. During oocyte maturation induced by hormone injection, cyclin A2 protein in oocyte of the gyno-carp remains at a relative high level throughout the whole maturation division. As for the gono-carp, cyclin A2 protein is up-regulated when the oocyte enters metaphase I and is down-regulated before the oocyte enters metaphase II. Western blotting analysis reveals that gono-carp stockpiles a large amount of cyclin A1 proteins in its fully grown oocyte, while the protein is under the detectable level in gyno-carp, which is not accordant with the result of Northern blotting. Through the discussions and analysis on the four genes, a hypothesis has been postulated on the meiosis I inhibition of the gynogenetic silver crucian carp.