Abstract: Using a vital staining technique the difference of potency was observed in yolk deposition into the oocytes during vitellogenesis rjr the housefly Musca dornestica vacina. The potency of yolk deposition could be observed in vitellogenic folhces, but not in prey and postvitellogenic foliicles. The uptake of viteltogenin reached maximum during stage 6 of ovarian development (48 hours after adult eclosion) which was in coincidence with the high potency observed, while vitellogenin uptake into the ovary during the pre and post-vitellogenic stages of oogenesis was hardlydetectable. The potency of yolk deposition was significantly increased when the ovaries were incubated in the cultural medium containing JH lIl. The level of Na⁺K⁺ ATPase activity in ovarian microsomal fractions rose andfell in concert with the vitellogenic stages of oocyte development. Our results showed that the enzymic activity in previtellogenic flies 24 hours after eclosion was low; it rose and reached the peak in the ovaries of the flies 48 hours after eclosionand then decreased sharply to a very low level in the flies 72 hours after eclosion. When JH was injected into or topically applied on the body of the fly 32 hours after eclosion, the enzymic activity of microsomal fractions was found higher than that of the fly 36 hours after eclosion. However, when JH was injected into or topically applied on the body of the fly 44 hours after eclosion, the enzymic activity was found lower than that of the fly 48 hours after eclosion. When JH was added to a microsomal fraction prepared from ovaries 36 and 48 hours after eclsion, the enzymic activities were increased by 295% and 350%, respectively. When vitellogenicovaries were incubated in the medium with the presence of JH (10 μg/μl), the enzymic activity increased by 1.26 fold in the homogenate. We infer from our results that JH is related to the potency of yolk deposition and increase of Na⁺K⁺ ATPase activity so as to regulate the uptake of vitellogenin by oocytes.

Key words: Musca domestica vacina——yolk deposition——JH III——Na+- K+ ATPase