Bronchial lympho-epithelial nodules in the rat: definition and morphological characteristics in optical and electron...

Three type of structures can be distinguished among the bronchial lymphoid tissue: lymph nodes, lymphoids cells aggregates and lymphoepithelial nodules. Such structures are encountered in many species and may be characterized by flattened epithelium, devoid of mucus producing cells, infiltrated with lymphocytes and containing of few ciliated cells. The lymphoepithelium surrounds the nodules, characterized by a high cellular density. Original structures may be observed, mainly inter and intracellular vacuoles. Peripheral lymphatic vessels and high endothelium veins contribute to the important lymphocyte transfer. Electron microscope, studies support the view that lymphoepithelium has an uptake function of particulate matter; more direct evidence is however attempted. An hypothesis of capacity for antigenic recognition of the lymphoepithelium nodules is discussed.