Androgen metabolism in the skin of the rainbow trout (Oncorhynchus mykiss).

Pieces of skin of male and female rainbow trout (Oncorhynchus mykiss) were incubated with testosterone and 11-ketotestosterone as substrates. In immature fish the conversion rate was low. In non-spawning adult males 11-ketotestosterone was reduced to 5α-11KDHT (up to 5.

Ontogeny of gonadotropin releasing hormone and gonadotropin immunoreactivity in brain and pituitary of normal and estrogen-treated guppies, Poecilia reticulata Peters.

Gonadotropin releasing hormone (GnRH) and gonadotropic hormone (GTH) were identified by immunohistochemistry in the brains and pituitaries of neonate, juvenile and adult guppies. GTH was present in some cells of the pars intermedia (pi) and proximal pars distalis (ppd) of all animals. GnRH was found in the perikarya of the nucleus olfactoretinalis.

The biosynthesis of 11-ketotestosterone by the testis of the Siamese fighting fish Betta splendens Regan (Anabantoidei, Belontiidae).

Testicular tissues of the Siamese fighting fish were incubated with [14C]pregnenolone for 10, 20, 30, 50, 80, and 120 min, and with [14C]progesterone, [14C]11 beta-hydroxyandrostenedione, [14C]11 beta-hydroxytestosterone, and [14C]androstenetrione for 120 min. 11-Ketotestosterone was the main metabolite in all 120-min incubations. No 11-oxygenated C21 steroids were found as metabolites of either pregnenolone or progesterone.

The occurrence of serological H-Y antigen (Sxs antigen) in the diandric protogynous wrasse, Coris julis (L.) (Labridae, Teleostei).

The serological sex-specific (Sxs) antigen (previously called 'H-Y antigen') has been shown, in various vertebrate species ranging from fish to mammals, to be characteristic of the heterogametic sex. We studied a protogynous hermaphrodite, Coris julis, in order to examine whether the change of a female to a secondary male also involves a change in the Sxs-antigen phenotype. The (homogametic) females of this species were found to be Sxs negative, while both primary and secondary males were Sxs positive.

In vitro studies on steroid metabolism by gonadal tissues from ambisexual teleosts. II. Conversion of [14C]androstenedione by the heterologous gonadal tissues of the protandric sea bream Pagellus acarne (Risso).

The heterologous gonadal tissues of the protandric sea bream Pagellus acarne were incubated with [14C]androstenedione in vitro. The tissues were taken from two males, an inverting specimen, and a female in early April. Although the testicular tissue regresses in the inverting fish the rate of 11 beta-hydroxylation in the male part of the gonad is at least as high as in the homologous portion of the "pure" male.