Study On Development Of The Gonad Of Hyriopsis Schlegelii

As a representative species of freshwater pearl mussels, Hyriopsis schlegelii has important commercial values. Study on the gonad development can provide theoretical references for conservation of germplasm resources, artificial breed and sex induction of H. schlegelii. So far, there were many researches had done about gonad development on the freshwater mussels, but about H. schlegeli very rare. In this experiment, the process of gonad development had been observed. The results can be briefly summarized as follow:1).Research on the Gonad developmentChanges in the gonad development of H. schlegelii, from two months to sixty months, were examined by histological observation. The results showed that the gonad development began at the 5 months and matured in the 36 months. Gonad outside wrapped in the visceral mass, consisted of follicle, genital canal and reproductive duct, it was grape-like or dendritic branch. After gonad matured, the gonad development has a reproductive cycle every year. According to the gonad development status, follicular cavity size, maturity of reproductive cells and so on, reproductive cycle can be divided into the following five stages:proliferating stage, growing stage, maturing stage, spawning stage and recovering stage. In the proliferating stage, the number of the follicles went up. In the growing stage, not only the number of follicles went up but also the size increased and in the maturing stage the cells of the gonad matured, where a lot of sperms or eggs can be seen. In the spawning stage the fullness of follicles decreased, and it appeared relaxation. In the resting stage, sperm or eggs were drained, and follicular atrophy. The gonad can go through each stage in Feb every year.2). Research on the hermaphroditic phenomenonBefore the sexual maturity, the gonad has been examined by histological observation. Result showed that during 26 to 32 months, hermaphroditic phenomenon can be observed in male. At the same time there were both the female and male follicles existence in a gonad, which follicles of female and male arranged in the form of mutual cross.3). Research on the gonad apoptosisThere was apoptosis at different stages of reproductive cycle in gonad after matured, which can be observed by Hochest33258 or acridine orange stained under the fluorescence microscope. The number of apoptosis cells increased with the development of gonad.The conclusion can be summed up as follow:the gonad appeared at the age of 5 months, matured at 36 months. After gonad matured, the gonad development has a reproductive cycle every year. The hermaphroditic phenomenon occurs during the age of 26 months to 32 months. The cell apoptosis exist in each stage of reproductive cycle and changes with the development of gonads.