HISTOLOGICAL STUDIES ON GONADAL DEVELOPMENT IN THE ENDEMIC TIBETAN FISH PTYCHOBARBUS DIPOGON

The histology of gonadal development in Ptychobarbus dipogon was studied by using conventional paraffin sections and HE staining, in order to obtain information on its reproductive systems useful for its artificial breeding. The results showed that the development of oocytes can be divided into five phases, and ovarian development can be divided into six stages. In stage V ovaries, ovum worship was found to occur, indicated by the 1.38 鲶1 ratio of small ova to large ova. Phase 3 oocytes were characterized by appearance of yolk granules and follicles; phase 4 oocytes by rapid increase of yolk granules, and the movement of the nucleus toward the animal poles; phase 5 by the fusion of yolk granules, and the separation of oocytes from follicular membranes to float in the ovarian cavity. Male P. dipogen had lobular testes, and their germ cells can be categorized into spermatogonia, spermatocytes; spermatids; and spermatozoa. Their testes also developed in six stages. The species followed a batch-synchronous spawning pattern.