Identification by immunofluorescence of ACTH-producing cells in the pituitary gland of the tree frog Hyla arborea

The indirect immunofluorescence procedure was used to localize ACTH-producing cells in the pituitary distal lobe from Hyla arborea adult specimens; the antiserum employed was rabbit anti-synthetic ACTH (1–24) conjugated with BSA. Immunohistochemical staining was suppressed by solid-phase absorption of the anti-ACTH with the specific antigen. In the distal lobe one cell population is immunoreactive; these cells are predominantly localized in the anterior half, both ventrally and dorsally; they exclusively correspond to type-3 basophils. In the intermediate lobe the total cell population is immunoreactive. Parallel inspections carried out on the pituitary of Xenopus laevis specimens gave results fully consistent with those reported by other authors.