The ovine bronchopulmonary lymph drainage pathways: a model to study pulmonary immune responses.

The lymph drainage pathways of all ovine bronchopulmonary segments (BPS) were traced following intrabronchial instillation of dyes and/or 125IUdR-labeled bacteria. The critical observation, relative to pulmonary immune apparatus, was the identification of at least three BPS-regional lymph node sets with nonoverlapping lymph drainage pathways: right cranial segment-cranial bronchial lymph node; left apical segment-caudal bronchial lymph node; and dorsal-basal, and accessory lobe segments-caudal mediastinal (caudal) lymph node. The efferent lymph drainage pathways from the pulmonary regional lymph nodes were also delineated. This anatomic information is being used to develop a model for studying the respective roles of intrapulmonary, regional, and systemic lymphoid tissues in pulmonary immune responsiveness.