title: The photoreceptive cells of the pineal gland in adult zebrafish (Danio rerio).
abstract: The zebrafish pineal gland plays a fundamental role in the regulation of the circadian rhythm through the melatonin secretion. The pinealocytes, also called photoreceptive cells, are considered the morphofunctional unit of pineal gland. In literature, the anatomical features, the cellular characteristics, and the pinealocytes morphology of zebrafish pineal gland have not been previously described in detail. Therefore, this study was undertaken to analyze the structure and ultrastructure, as well as the immunohistochemical profile of the zebrafish pineal gland with particular reference to the pinealocytes. Here, we demonstrated, using RT-PCR, immunohistochemistry and transmission electron microscopy, the expression of the mRNA for rhodopsin in the pineal gland of zebrafish, as well as its cellular localization exclusively in the pinealocytes of adult zebrafish. Moreover, the ultrastructural observations demonstrated that the pinealocytes were constituted by an outer segment with numerous lamellar membranes, an inner segment with many mitochondria, and a basal pole with the synapses. Our results taken together demonstrated a central role of zebrafish pinealocytes in the control of pineal gland functions.
authors.affiliation: Dipartimento di Morfologia, Biochimica, Fisiologia e Produzione Animale, Sezione di Morfologia, Università di Messina, Italia.
authors.forename: Rosaria
authors.initials: R
authors.lastname: Laurà
authors.forename: Domenico
authors.initials: D
authors.lastname: Magnoli
authors.forename: Rosalia
authors.initials: R
authors.lastname: Zichichi
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Guerrera
authors.forename: Felix
authors.initials: F
authors.lastname: De Carlos
authors.forename: Alberto Álvarez
authors.initials: AÁ
authors.lastname: Suárez
authors.forename: Francesco
authors.initials: F
authors.lastname: Abbate
authors.forename: Emilia
authors.initials: E
authors.lastname: Ciriaco
authors.forename: Jose Antonio
authors.initials: JA
authors.lastname: Vega
authors.forename: Antonino
authors.initials: A
authors.lastname: Germanà
mesh_terms: D000818:Animals; D007150:Immunohistochemistry; D046529:Microscopy, Electron, Transmission; D020419:Photoreceptor Cells, Vertebrate / Q000648:ultrastructure*; D010870:Pineal Gland / Q000166:cytology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012243:Rhodopsin / Q000032:analysis / Q000378:metabolism; D015027:Zebrafish / Q000033:anatomy & histology*
chemical_list: D012243:Rhodopsin