Effects of androstenedione, 19-norethynyltestosterone, progesterone, and medaka, Oryzias latipes.

Abstract

Effects of androstenedione, 19-norethynyltestosterone, progesterone, and 17α-hydroxyprogesterone upon the manifestation of secondary sexual characters were studied in the orange-red variety of the medaka. The steroids were consecutively administered per os for 15 days. Androstenedione and 19-norethynyltestosterone induced formation of new segments in the fin rays and produced papillar processes on the anal fin of the female. 19-norethynyltestosterone proved to have a strong potency, estimated to be more than 300 times that of androstenedione. Progesterone and 17α-hydroxyprogesterone had neither androgenic nor estrogenic effect on the secondary sexual characters. This is quite in harmony with the fact that they have neither androtermonic nor gynotermonic potency. The administration of these steroids did not impair the fertility of females. The administered females produced offspring by mating with administered males.