EFFECTS OF HORMONIC STEROIDS ON OVARIAN GROWTH OF ADULT ORYZIAS LATIPES IN SEXUALLY INACTIVE SEASONS

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Abstract
Results of experiments presented in this paper seem to show that the implants of pellets of some hormonic steroids inhibit the development of winter ovaries of adult Oryzias which usually takes place when the fish are subjected to high temperature (23-27[degree]C). Estrone is the most potent in suppressing the ovarian development. Testosterone propionate and desoxycorticosterone acetate are less effective, and progesterone and cholesterol are almost inactive in this respect. Development of ovaries of warmed winter fish is also inhibited when the fish are reared in water containing estradiol at concentrations of 0.2, 0.06 or 0.02 mg/1. Concentration of 0.004 mg/1. is ineffective. No evidence for the promotion of ovarian growth by hormonic steroids was obtained in Oryzias, under these experimental conditions. The present experiments seem to indicate that the hormonic steroids are capable of inhibiting ovarian growth in winter specimens of Oryzias, in light as well as in darkness.