Pituitary control of pigmentation in xanthic, moor, and white Carassius auratus L

After hypophy sectomy some of the melanophores in moor fantail goldfish (Carassius auratus L.) underwent lysis and the remaining cells showed melanin aggregation. The orange colour in xanthic. moor, and white fantail varieties of goldfish 'pales' after hypophysectomy. Homogenates of whole pituitary, pars distalis, or neurointermediate lobe tissue given as intraperitoneal injections effected a marked increase in the melanophore index in hypophysectomized moor fantails and intensified the orange colour in hypophy sectomized moor and xanthic fantails.Ovine prolactin, ovine thyrotrophs (TSH), ovine somatotrophs (STH), and a combination of ovine luteinizing hormone (LH) and porcine follicle-stimulating hormone (FSH) were effective in increasing the melanophore index in hypophy sectomized moor fantails. Of these four preparations the LH–FSH combination was the most potent. Saline and thyroxine were without effect.Ovine prolactin, ovine STH. and a combination of ovine LH and porcine FSH restored the orange colour of hypophysectomized xanthic and moor fantails. Of these three preparations the LH–FSH was most potent. Saline, ovine TSH. and thyroxine were without effect.Differences were found in the apparent activity of prolactin, thyrotroph, gonadotroph, and putative melanocyte-stimulaling hormone (MSH) cells in the pituitaries of the three varieties of goldfish but these could not be directly correlated with pigmentation differences between the groups.