M-cell subsets in SCID mice nasal tonsil

摘要

It is known that the lymph nodes and Peyer's patches in SCID mice are remarkably atrophic, however, no data have been reported about the morphology of NALT as a principal mucosal lymphoid tissue in the respiratory tract of rodents. Light, transmission electron microscopy and immunohistochemical studies were carried out on 10 SCID mice in Prof. Mogi's laboratory. Cell aggregates, composed mainly of macrophages and neutrophils, were detected beneath the epithelial layer around the nasopharyngeal duct entrance. Immunohistochemically, we confirmed the absence of surface IgA, IgG and IgM in the NALT and spleen of SCID mice. We found the presence of M-cellular epithelium overlying mesenchymal cell aggregates. This epithelium consisted of 4 M-cell subsets: Ml-stem cells, M2, M3 and M4. We regard the diversity of M-cells population as a result of subset super-specialization during evolution. We suggest that the localization and morphological features of mucosa-associated lymphoid aggregates as self-standing lymphoid organs (specific epithelium and stroma) could be attributed to the presence of M-cells and corresponding fibroblastic reticulum cells.