title: Immuno-electron-microscopic localization of enkephalin in the secretory granules of C cells in the chicken ultimobranchial glands.
abstract: In the chicken, enkephalin-immunoreactive cells and nerve fibers are distributed in the ultimobranchial glands, which consist of C-cell groups and cyst structures. Ultrastructural features of the enkephalin cells and nerve fibers were examined by immuno-electron microscopy using both the streptavidin-biotin-peroxidase method and the protein A-colloidal gold method. Immunoreactivity for enkephalin was located on the secretory granules of C cells. In 1-day-old chickens, three types of C cells were distinguished on the basis of their granule size. Type-I cells were filled with large secretory granules (200-600 nm in diameter). These elements represented a majority of the C-cell population. Type-II cells contained medium-sized granules (100-280 nm in diameter). Type-III cells displayed small secretory granules (60-200 nm in diameter). The latter cells were elongate or irregular in shape and frequently extended cytoplasmic processes into the connective tissue stroma or contacted other C cells. Enkephalin-immunoactivity was revealed by dense deposits of immunogold particles on the secretory granules of type-II and type-III cells. There were only a few type-I cells showing immunoreactivity for enkephalin. A double immunogold labeling procedure demonstrated that calcitonin and enkephalin were colocalized in the same secretory granules of type-I and type-II cells. Type-III cells were devoid of immunoreactivity for calcitonin. Enkephalin-immunoreactive nerve fibers were characterized by the presence of granular vesicles, 60-160 nm in diameter, and frequently established direct contact with the surface of C cells.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Anatomy, Kitasato University School of Medicine, Kanagawa, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kameda
authors.forename: C
authors.initials: C
authors.lastname: Hirota
authors.forename: M
authors.initials: M
authors.lastname: Murakami
mesh_terms: D000818:Animals; D002116:Calcitonin / Q000737:chemistry; D002645:Chickens; D003594:Cytoplasmic Granules / Q000737:chemistry*; D004745:Enkephalins / Q000032:analysis*; D005260:Female; D017979:Gold Colloid; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D008297:Male; D016253:Microscopy, Immunoelectron; D009412:Nerve Fibers / Q000737:chemistry / Q000648:ultrastructure; D014460:Ultimobranchial Body / Q000737:chemistry* / Q000294:innervation / Q000648:ultrastructure
chemical_list: D004745:Enkephalins; D017979:Gold Colloid; D002116:Calcitonin