The Study Of Gonadal Development And Artificial Propagation Of Acrossocheilus (lissochilichthys) Hemispinus

In this paper, gonadal differentiation, development and annual change were investigated in the teleost, Acrossocheilus (Lissochilichthys) hemispinus using histological methods. On the basis of the above research, wild Acrossocheilus (Lissochilichthys) hemispinus were caught and carried on domestication cultivation, artificial propagation and development of embryos and larvae. The activity and location of P450 aromatase was studied in gonadal development by immunohistochemistry.The observation of gonadal development showed that the PGCs lacated in the peritoneal epithelium and splanchnic mesoderm beside alimentary canal on day 4. The genital ridge was formed on day 15, and then, the PGCs went into the genital ridges and formed the primordial gonads on day 20. On day 40, the primordial gonads began to differentiate and the gonads has clearly divided into testes and ovaries on day 60. Ovarian development of Acrossocheilus (Lissochilichthys) hemispinus can be divided into 6 stages:the stagel only appeared in the fry. The annual variation of the ovarian development in the sexually mature fishes experienced stageⅡ-Ⅵ, and the ovarian mature coefficient changed between 0.72%～6.66%. Testes development is also divided into 6 stages; the stageⅠ,Ⅱonly appeared in the fry. The testes of the annual development can produced different amounts of sperms, and the testis mature coefficient varied between 0.53%～3.63%.The wild Acrossocheilus (Lissochilichthys) hemispinus were domesticated and cultivated in the cement pond until they can normally feed and grow to reach the sexual maturity. The domesticated fishes were induced to spawn for 4 times. It also indicated that 25779 eggs and 8217 larvae were obtained, and the rates of hatching and germination were 80.0% and 43.8%, respectively. When the water temperature is 25-28℃, the effect time of the hormone is 24-30h, and the eggs needed 62h from fertilization to hatching. After the larvae were cultivated for 55-65d, the full-length of the fry is 25.0-35.0mm.The P450 aromatase was mainly orientated in the cytoplasm of the phaseⅡoocytes and the follicular layer of the phaseⅢoocytes in the ovaries, and not expressed in the phase IVoocytes. The activity of P450 aromatase peaked in the phaseⅡ,Ⅲof ovarian development, and gradually weakened with ovarian development. The P450 aromatase activity in the testis mainly expressed in the membranes of the spermatogonia, spermatocytes and interlobular septum. The P450 aromatase activity was expressed variably at different stages of testis development. The results suggest that P450 aromatase mainly involved in the development process of eggs, but its role is not clear in the testis development.