Temporospatial characterization of the bronchus associated lymphoid tissue (BALT) of the one humped camel (Camelus dromedarius)

BACKGROUND: Bronchial-associated lymphoid tissue (BALT) is responsible for the local immune response of the lung against airborne infections. The structure of this tissue varies according to species and age. AIM: The aim of this study was to describe the possible age-related structural variation of the BALT of the one humped camel. MATERIAL AND METHODS: Fresh specimens from both lungs of 15 clinically healthy male camels (10 months–12 years) were studied with light and electron microscopes. RESULTS: The BALT in the camel was variable from few lymphocytes to well-organized lymphoid tissue with a clear germinal center. The BALT of the bronchi is a constant lymphoid tissue in young and adult camels which may be of the large size with clear germinal center in response to repeated immune reaction and involutes in old age. The BALT of the bronchioles may be induced and develops mainly due to an immune reaction and showed great morphological variations and observed in different ages. High endothelial venules were associated with BALT in the bronchi but not with that of the bronchioles. The BALT-associated epithelium was tall pseudostratified columnar ciliated epithelium with goblet cells in the extrapulmonary bronchi changed to pseudostratified columnar ciliated epithelium mucous secreting cells in the intrapulmonary bronchi and simple columnar ciliated to simple cuboidal epithelium with Clara cells without goblet cells or mucous secreting cells in the bronchioles. CONCLUSIONS: The BALT of the bronchi is a constant lymphoid tissue in young and adult camels and involutes in old age. The BALT of the bronchioles may be induced and develops mainly due to an immune reaction and observed in different ages.