No abstract

No abstract

Square College, iV?w P o r k Dnzversity ONE PLATE (FOUR FIGURES)This study is complementary to the previously reported effects of estrogens (Berkowitz, '38) and androgens (Eversole, '39) on the gonads and secondary sex characters of the small tropical fish, Lebistes reticulatus (guppy).Briefly stated, our previous experiments demonstrated that the feeding of estrogens to newly born fish inhibited the development of male secondary sex characters, and stimulated the development of female secondary sex characters so that all such treated animals took on a female appearance. There was an inhibition of the testes in both mature and immature animals and the production of an ovotestis in about 50% of the genetic males. The effects on the ovary were less marked and irregular. Comparable studies were made by Eversole ( '39), using testosterone propionate. Similar work concerning estrogen and androgen effects in fish has been reported (Padoa, '37; Castelnuovo, '37; Witschi and Crown, '37; Regnier, '38 ; Baldwin and Goldin, '39).The present investigation involves the use of a variety of crystalline estrogens. Our particular purpose was an attempt, by varying dosage, duration, and mode of administration of treatment, to obtain a more complete and more consistent sex reversal in the gonad than heretofore obtained.