title: Antigen-sampling cells in the salmonid intestinal epithelium.
abstract: Antigen uptake has been shown to occur in the teleost intestine, but so far, limited information is available on the distribution and nature of cells involved in the process, and M cells, known for their antigen-sampling abilities in mammals, have not been identified. Here, different intestinal segments from salmonid fish were exposed to gold-BSA to identify antigen-sampling cells. Sections from exposed intestine were examined by light and electron microscopy. Uptake of gold-BSA was restricted to very few dendritic-like cells and to a limited number of epithelial cells located in the mucosal folds in the second segment of the mid-intestine. Gold-positive epithelial cells displayed diverging and electron-dense microvilli with channels intruding into the cytoplasm. A lectin binding experiment demonstrated the presence of cells with mammalian M-cell characteristics in the identical regions. As the identified epithelial cells shared some morphological similarities with immature mammalian M cells, this phenotype may represent evolutionary early antigen-sampling enterocytes.
authors.affiliation: Section of Anatomy and Pathology, Institute of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, Ullevålsveien 72, Oslo, Norway.
authors.forename: Bjørn
authors.initials: B
authors.lastname: Fuglem
authors.forename: Emilio
authors.initials: E
authors.lastname: Jirillo
authors.forename: Inge
authors.initials: I
authors.lastname: Bjerkås
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kiyono
authors.forename: Tomonori
authors.initials: T
authors.lastname: Nochi
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Yuki
authors.forename: Martin
authors.initials: M
authors.lastname: Raida
authors.forename: Uwe
authors.initials: U
authors.lastname: Fischer
authors.forename: Erling Olaf
authors.initials: EO
authors.lastname: Koppang
mesh_terms: D056704:Adaptive Immunity / Q000276:immunology; D000818:Animals; D000941:Antigens / Q000276:immunology*; D020895:Enterocytes / Q000166:cytology / Q000276:immunology* / Q000648:ultrastructure; D007413:Intestinal Mucosa / Q000166:cytology / Q000276:immunology* / Q000648:ultrastructure; D037102:Lectins / Q000276:immunology; D018613:Microscopy, Confocal / Q000662:veterinary; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D046529:Microscopy, Electron, Transmission / Q000662:veterinary; D012487:Salmonidae / Q000276:immunology*
chemical_list: D000941:Antigens; D037102:Lectins