title: Colocalization of heparin and histamine in the intracellular granules of test cells from the invertebrate Styela plicata (Chordata-Tunicata).
abstract: In most ascidian species the oocytes are surrounded by two types of accessory cells called follicle cells and test cells. Test cells are located on the periphery of oocytes and remain in the perivitelline space during egg development until hatching. Heparin and histamine were previously described in the test cells of the ascidian Styela plicata. In the present study, electron microscopy techniques were used to characterize the ultrastructure of the S. plicata test cells and to localize heparin and histamine in these cells. Test cells contain several intracellular granules with unique ultrastructural features. They are formed by elongated filaments composed of serial globules with an electron-lucent circle, containing a central electron-dense spot. Immunocytochemistry showed that heparin and histamine colocalize at the border of granule filaments in the test cell. Compound 48/80, a potent secretagogue of heparin-containing mast cells, also induced degranulation of test cells. According to these results, we suggest that test cells represent ancient effector cells of the innate immunity in primitive chordates.
authors.affiliation: Laboratório de Tecido Conjuntivo, Hospital Universitário Clementino Fraga Filho and Departamento de Bioquímica Médica, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Moisés C M
authors.initials: MC
authors.lastname: Cavalcante
authors.forename: Leonardo R
authors.initials: LR
authors.lastname: de Andrade
authors.forename: Claudia
authors.initials: C
authors.lastname: Du Bocage Santos-Pinto
authors.forename: Anita H
authors.initials: AH
authors.lastname: Straus
authors.forename: Hélio K
authors.initials: HK
authors.lastname: Takahashi
authors.forename: Silvana
authors.initials: S
authors.lastname: Allodi
authors.forename: Mauro S G
authors.initials: MS
authors.lastname: Pavão
mesh_terms: D000818:Animals; D015550:Cell Degranulation / Q000187:drug effects; D003594:Cytoplasmic Granules / Q000737:chemistry* / Q000187:drug effects / Q000648:ultrastructure; D006493:Heparin / Q000032:analysis*; D006632:Histamine / Q000032:analysis*; D010063:Ovum / Q000737:chemistry / Q000166:cytology; D014561:Urochordata / Q000737:chemistry* / Q000166:cytology; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology
chemical_list: D003189:p-Methoxy-N-methylphenethylamine; D006632:Histamine; D006493:Heparin