title: The histological features of the immune system of the equine respiratory tract.
abstract: The distribution of mucosa-associated lymphoid tissue along the equine respiratory tract was surveyed in light microscopical sections. Intra-epithelial lymphocytes and similar cells scattered in the lamina propria were identified in all sites from the nasal vestibule to bronchioles of 2 to 4 mm diameter. Isolated lymphoid patches, occasionally with nodules, were common in bronchioles, but the density of this bronchiole-associated lymphoid tissue (BRALT) varied between individual horses. Bronchus-associated lymphoid tissue (BALT) was infrequently encountered. In the upper respiratory tract, nodules dispersed within the nasal cavity, nasopharynx and near the auditory tube merit the collective term, nasal-associated lymphoid tissue (NALT). Laryngeal- and tracheal-associated lymphoid tissue (LTALT) was also identified, but this was limited to the epiglottis, arytenoid and rostral trachea. At all sites, the discrete lymphoid masses comprise primary or secondary nodules, a parafollicular and a dome area. The airway lining above was frequently modified into a lympho-epithelium and also showed varied patterns of infolding which might enhance antigen trapping.
authors: Department of Veterinary Medicine, University of Bristol, School of Veterinary Science, Langford, U.K.
authors: T S
authors: TS
authors: Mair
authors: E H
authors: EH
authors: Batten
authors: C R
authors: CR
authors: Stokes
authors: F J
authors: FJ
authors: Bourne
mesh_terms: D000818:Animals; D004847:Epithelial Cells; D005260:Female; D006736:Horses / Q000276:immunology*; D008214:Lymphocytes / Q000166:cytology / Q000276:immunology*; D008297:Male; D009092:Mucous Membrane / Q000166:cytology / Q000276:immunology; D009928:Organ Specificity; D012137:Respiratory System / Q000166:cytology / Q000276:immunology*