Biology of Reproduction, Vol 1, 272-281, Copyright © 1969 by Society for the Study of Reproduction

The Role of Pituitary and Gonadal Hormones in the Differentiation of Testis and Secondary Sex Characters of the Juvenile Guppy Poecilia reticulata Peters

¹ Department of Zoology, University of British Columbia, Vancouver, British Columbia

Hypophysectomy of the juvenile guppy prevents the development of both gametogenetic and endocrine tissues of testis as well as the differentiation of secondary sex characters. Administration of methyl testosterone to hypophysectomized juveniles for 8 weeks stimulates the differentiation of the sperm ducts and secondary sex characters but has no effect on either spermatogenesis or the differentiation of interstitial cells. Two doses of methyl testosterone (1:2 x 10⁶ and 1:10⁷) were used but no differences in results were evident. Although these results are based on only five hypophysectomized male juveniles, they are highly consistent and significant when compared with the controls. Details of the technique for the hypophysectomy of the juvenile guppy are described.