Pulmonary argyrophil cells at high altitude.

The numbers of individual argyrophil cells and groups of argyrophil cells were compared in rabbits which had been born and had spent their entire lives at a height of 4300 m above sea level and in sea-level controls. In the bronchi and bronchioles there were more groups of argyrophil cells in the high-altitude rabbits (mean 10-23/cm2) than in the sea-level controls (mean 5-22/cm2). In the alveolar walls there were more individual cells in the high-altitude rabbits (mean 2-65/cm2) than in the sea-level controls (mean 0-72/cm2). These differences may be either inherited or acquired and in either case, it is suggested that the likely explanation for the differences is hypoxia. If acquired, the differences may be due to differentiation of argyrophil cells from a stem cell. The results provide evidence that individual argyrophil cells exist in the alveolar walls. They suggest that individual argyrophil cells and groups of argyrophil cells may have different functions according to their site.