title: Immunoreactive Met-enkephalin-like material in the testis of Rana esculenta: identification and localization.
abstract: Methionine-enkephalin (Met-Enk) has been detected in the testis of the frog, Rana esculenta, using a reverse-phase high-performance liquid chromatography system coupled with a specific radioimmunoassay. By means of immunocytochemical techniques Met-Enk positive cells have been localized in interstitial and germinal compartments. Particularly, spermatogonia, spermatocytes, and spermatozoa were stained in seminiferous tubules, and numerous interstitial cells showed strong cytoplasmic immunoreactivity in summer animals. Variations in the concentration of Met-Enk immunoreactive material occurred during the annual cycle. Our data show that Met-Enk is present in testes of nonmammalian vertebrate species. These results suggest that autocrine and/or paracrine mechanisms may regulate testicular activity in amphibians.
authors.affiliation: Istituto di Anatomia Comparata, Università di Genova, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Vallarino
authors.forename: M
authors.initials: M
authors.lastname: Pestarino
authors.forename: M
authors.initials: M
authors.lastname: D'Antonio
authors.forename: S
authors.initials: S
authors.lastname: Fasano
authors.forename: F
authors.initials: F
authors.lastname: Facchinetti
authors.forename: R
authors.initials: R
authors.lastname: Pierantoni
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003593:Cytoplasm / Q000378:metabolism; D004744:Enkephalin, Methionine / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D008969:Molecular Sequence Data; D011863:Radioimmunoassay; D011893:Rana esculenta; D013737:Testis / Q000033:anatomy & histology / Q000378:metabolism*
chemical_list: D004744:Enkephalin, Methionine