Directions of Mucous Surface Waves in Large Bronchi Are Different between Human Beings and Quadrupeds

The purpose of this study was to investigate the directions of mucous surface waves and mucous flow in the large bronchi. The materials were tracheae, carinae, and main bronchi of 12 humans, 5 pigs, 3 monkeys, and 1 rabbit. Mucous surface waves and mucous flow were observed with a stereoscopic zoom microscope system. Large differences in the directions of mucous surface waves between human beings and quadrupeds were encountered. In the trachea of quadrupeds, the mucous surface waves of both the right and left walls fused at the midline of the ventral side and then proceeded in an upward fashion, and those waves of the membranous portion proceeded upward synchronously. In the trachea of human beings, those waves proceeded in a clockwise helical fashion to the oral side. In the main bronchi of them, those waves traveled in a straight, upward fashion. There were no significant differences between the directions of mucous surface waves and mucous flow in any portion of the trachea. When the surface of the specimen was covered with sticky mucous, an abnormal to-and-fro pattern of movement was observed. There was a difference in transport of the foreign bodies and sputum in the large bronchi between human beings and quadrupeds.