Immunocytochemical study of pituitary FSHß and LHß cells during the ontogeny of the toad Bufo arenarum

The ontogeny of gonadotrophs in the pituitary of Bufo arenarum was studied by immunocytochemical techniques using monoclonal antibodies against bullfrog lutropin s-subunit and bullfrog follitropin s-subunit. The first appearance of immunoreactive gonadotropic cells was at midprometamorphosis in the caudal zone of the pars distalis. During metamorphosis, in juveniles and especially in adult animals, follicle stimulating hormone (FSH) and luteinizing hormone (LH) producing cells were distributed throughtout the gland. The number of these cells was greatly increased in older stages. In all the stages studied colocalization of FSH and LH was observed. At least three types of gonadotrophs were identified: the first cell type containing only FSH; the second only LH; and the third, FSH and LH in the same cell.