Progesterone-dependent and -independent avidin production in chick oviduct organ culture

Progesterone-dependent and -independent avidin inductions were found in chick oviduct culture. The effects of oestrogen priming and actinomycin D on these inductions were studied. Priming comprised daily diethylstilboestrol (DES) injections in vivo and one day's incubation in vitro with DES before experimental treatment. After 0 or 1 day of DES pretreatment no measurable amount of avidin was found. Avidin was present in progesterone-untreated incubated tissues after 4 days' DES pretreatment. Incubation with progesterone for 24 h increased avidin levels only after 4 or more days of oestrogen priming. No induction of avidin by actinomycin D similar to that found in vivo was observed in vitro. Actinomycin D inhibited both progesterone-dependent and -independent avidin production, but this effect diminished as oestrogen pretreatment was prolonged. Actinomycin D also significantly reduced total oviductal RNA synthesis. It is concluded that oestrogen priming enhances both progesterone-dependent and -independent avidin production in vitro and that both inductions are partially dependent on new RNA synthesis.