The role of pituitary and gonadal hormones in the differentiation of testis and secondary sex characters of the juvenile guppy Poecilia reticulata peters.

Abstract

Vivien (1941) seems to have been the only investigator to use juvenile teleosts (Gobius paganellus) in an attempt to analyze the role of the pituitary in development of sex. This study, however, only demonstrated that hypophysectomy prevented the development of the gonad but provided no details of the regulation of cytogenesis in the testis or the control of secondary sex characters. Yet, juvenile fishes prior to the differentiation of the endocrine system offer unique advantages in attempts to analyze the hormonal regulation of reproductive functions. Tissues at this stage have never been stimulated by the hormones and there are no possibilities of the residual hormones in the organism which may interfere with the analysis of the