PULMONARY NEUROEPITHELIAL BODIES IN NEONATAL AND ADULT DOGS - HISTOCHEMISTRY, ULTRASTRUCTURE, AND EFFECTS OF UNILATERAL HILAR LUNG DENERVATION

In neonatal dogs, neuroepithelial bodies (NEB) are located in the dist al lung. They consist of closely packed and granulated epithelial cell s showing a positive immune reaction to serotonin and carrying well-de veloped apical microvilli. They make close contact with capillaries an d form morphologically afferent synaptic junctions with intracorpuscul ar nerve endings. Since most nerve endings degenerate after hilar lung denervation, they are carried by extrinsic, most likely vagal, sensor y nerve fibers. We conclude that pulmonary NEB probably are receptor o rgans, sampling the inspired air and secreting bioactive substances. T hese might have a local vaso- or bronchoactive regulatory effect, or c ould be carried to other body parts via the blood vessels. In addition , NEB might induce integrative reflexes via the central nervous system . The NEB intracorpuscular nerve endings also show spontaneous degener ation. This, in addition to the scarcity of NEB in the distal lungs of adult dogs, strongly suggests that the pulmonary NEB are particularly important during the perinatal period of life.