title: Demonstration of dopamine in electron-dense synaptic vesicles in the pars intermedia of Xenopus laevis, by freeze substitution and postembedding immunogold electron microscopy.
abstract: The presence of dopamine in the pituitary of the clawed toad Xenopus laevis was studied by light and electron microscope immunocytochemistry, using pre- and postembedding techniques. Light microscopy showed the presence of an intricate, anti-dopamine-positive fibre network throughout the pars intermedia. In preembedded stained material, dopamine appeared to occur in varicosities which make synaptic contacts with both folliculo-stellate cells and melanotrope cells. Post-embedding immunogold staining of freeze-substituted material permitted the localization of anti-dopamine reactivity in electron-dense vesicles in these varicosities. This finding supports the hypothesis that dopamine is involved in the (inhibitory) control of melanotrope cell activity in X. laevis.
authors.affiliation: Department of Animal Physiology, Faculty of Science, University of Nijmegen, The Netherlands.
authors.forename: F J
authors.initials: FJ
authors.lastname: van Strien
authors.forename: E P
authors.initials: EP
authors.lastname: de Rijk
authors.forename: P S
authors.initials: PS
authors.lastname: Heymen
authors.forename: T G
authors.initials: TG
authors.lastname: Hafmans
authors.forename: E W
authors.initials: EW
authors.lastname: Roubos
mesh_terms: D000818:Animals; D015925:Cryopreservation; D004298:Dopamine / Q000032:analysis*; D007150:Immunohistochemistry; D010902:Pituitary Gland / Q000737:chemistry* / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000737:chemistry* / Q000648:ultrastructure; D016610:Tissue Embedding / Q000379:methods; D014981:Xenopus / Q000033:anatomy & histology*
chemical_list: D004298:Dopamine