PUBERTAL DEVELOPMENT OF MALE AFRICAN CATFISH, CLARIAS-GARIEPINUS - IN-VITRO STEROIDOGENESIS BY TESTIS AND INTERRENAL TISSUE AND PLASMA-LEVELS OF SEXUAL STEROIDS

In fish, sex steroids initiate and/or accelerate the maturation of the brain-pituitary-gonad axis. In order to obtain information on the ste roid milieu during the pubertal development of male African catfish, w e have monitored the conversion of [H-3]-pregnenolone and [H-3]-andros tenedione by testis and [H-3]-pregnenolone by interrenal tissue fragme nts in vitro. Pubertal development occurs between two and six months o f age. Testicular development proceeds through four main stages that a re characterised histologically by the presence of spermatogonia (stag e I), spermatogonia and spermatocytes (stage II), spermatogonia, sperm atocytes and spermatids (stage III), and all germ cells including sper matozoa (stage IV). 11 beta-Hydroxyandrostenedione and cortisol were t he main products of testes and interrenal tissue, respectively, in all stages of the pubertal development; a change in the steroidogenic pat tern was not observed during this period. The interrenal tissue displa yed no significant conversion of [H-3]-pregnenolone to Ii-oxygenated a ndrogens. Blood plasma was analyzed for the presence of five androgens ; testosterone, 11 beta-hydroxytestosterone, 11 beta-hydroxyandrostene dione, androstenetrione, and 11-ketotestosterone. 11-Ketotestosterone was the quantitatively dominating androgen in the circulation at all s tages of development, which was more pronounced in stages III and IV. The obvious differences between the in vitro and in vivo results, name ly 11 beta-hydroxyandrostenedione being the main testicular product vs . 11-ketotestosterone dominating in the blood,may indicate that 11 bet a-hydroxyandrostenedione is converted to 11-ketotestosterone at extrat esticular sites.