Ultrastructural studies on the neuromuscular control of human tracheal and bronchial muscle

This study presents an ultrastructural analysis of neural and myogenic control of smooth muscle in human trachea, in small (approximately fourth to seventh order) bronchi. A moderate frequency of gap junctions between smooth muscle cells and a sparse innervation was observed in trachea. In contrast, small junctions without identifiable gaps were identified in bronchi along with a dense, sometimes close innervation of muscle. Most profiles of …