Comparison of avidin induction in the differentiated and undifferentiated chick oviduct by progesterone, actinomycin D and oviductal injury.

Various oestrogen (diethylstilboestrol, DES) pre-treatments were carried out on chicks and the production of avidin in the oviduct was induced by progesterone, actinomycin D or oviductal injury. Avidin induction was dose-dependent at doses between 5 mg and 40 mg progesterone/kg or 50 micrograns and 300 micrograms actinomycin D/kg respectively. The induction by oviductal injury correlated with the magnitude of tissue injury. First signs of avidin induction were seen at 4 h after oviductal injury, 12 h after progesterone or 12--16h after actinomycin D administration. Actinomycin D (200 micrograms/kg), when administered after progesterone injection, did not increase avidin induction by progesterone, this indicating that avidin induction by actinomycin D is not a "superinduction" effect. Evidence is presented here that the mechanism of avidin induction by oviductal injury and actinomycin D differs from that by progesterone. The differentiation of the oviduct caused by DES treatment was necessary for the induction by progesterone, whereas actinomycin D and oviductal injury also induced avidin in the undifferentiated or poorly differentiated oviduct. Simultaneous DES stimulation potentiated induction by progesterone but not by actinomycin D or oviductal injury. Furthermore, single prior DES stimulation increased avidin induction in the differentiated oviduct of DES-withdrawn chicks caused by progesterone but not that by actinomycin D or oviductal injury.