Histology and immunohistochemistry of bronchus associated lymphoid tissue (BALT) in the rat.

Bronchus associated lymphoid tissue (BALT) is present in the lungs of most mammals, closely associated with the bronchus epithelium (1). It has been suggested that BALT plays an important role in mucosal immunity (2,3). The purpose of the present study was to investigate the lymphoid and nonlymphoid elements of BALT in the rat, paying special attention to the status of BALT as peripheral lymphoid tissue.