Vimentin-positive cells in the epithelium of rabbit ileal villi represent cup cells but not M-cells.
Membranous (M)-cells are specialized epithelial cells of the Peyer's patch domes that transport antigens from the intestinal lumen to the lymphoid tissue. Vimentin is a reliable marker for M-cells in rabbits. Using immunohistochemistry (IHC), a subpopulation of epithelial cells has recently been identified in ordinary rabbit ileal villi, which are vimentin-positive and share morphological characteristics with the M-cells of the domes. To test the hypothesis that these cells represent M-cells outside the organized lymphoid tissue, lectin labeling and tracer uptake experiments were performed. Lectins specific for N-acetyl-glucosamine oligomers selectively bound to the vimentin-positive villous cells but not to M-cells in the domes. Microbeads instilled into the ileal lumen were taken up by M-cells within 45 min but not by the vimentin-positive cells in the villi. Lectin-gold labeling on ultrathin sections revealed that the lectin binding sites were located in the brush border and in vesicles in the apical cytoplasm. The vimentin/lectin-positive cells shared ultrastructural characteristics with the so-called "cup cells." We conclude (a) that the vimentin-positive cells in ordinary villi represent cup cells but not M-cells, (b) that they are readily detectable by (GlucNAc)(N)-specific lectins, and (c) that they do not transcytose experimental tracers. Although the specific function of cup cells is still obscure, they most probably represent a cell type distinct from M-cells of the domes with respect to both function and expression of the two new markers.
Ramirez
Carolina
C
Institute of Anatomy, University of Lübeck, 23538 Lübeck, Germany.
Gebert
Andreas
A
D000818:Animals; D007082:Ileum / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D037102:Lectins / Q000378:metabolism; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008871:Microvilli / Q000378:metabolism / Q000648:ultrastructure; D011817:Rabbits; D014746:Vimentin / Q000378:metabolism*
D037102:Lectins; D014746:Vimentin