Abstract: Oostatic hormone is one of the key factors regulating the cyclicity ofovarian development in most insects. In housefly, Musca domestica vicina, when the first cycle oocytes are in vitellogeic stage or postvitellogenic stage, the second cycle oocytes cannot develop into vitellogenic stage, and there is no vitellin deposition in the second cycle oocyte. When semipurified oostatic hormone extracted from matureovary was injected into flies 12 hours after emergence with a doseage of one pair ovary/fly, oocyte development was obvious inhibited. Twenty-four hours after the injection, the revitell'ogenic development of oocyte was inhibited. When vitellogeninsynthesis was initiated, the injected oostatic hormone inhibited vitellogenin synthesis in the fat body, lowered vitellogenin titer in the haemolymph, and thus caused the detay of vitellin deposition in the oocyte. Vitellogenin uptake was not inhibited by the oostatic hormone. EDNH could restore the development of oocyte inhibited byoostatic hormone. Oostatic hormone is not species-specific.

Key words: Musca domestica vicina, vitellogenesis, oostatic hormone, vitellin, vite- llogenin, EDNH