APUD cells and neuroepithelial bodies in hamster lung: methods, quantitation, and response to injury.

A comparative study of the Falck-Hillarp Technique, a modification of Eaton-Fedde procedure and silver staining of aldehyde-fixed tissue was carried out to determine the most efficient procedure to demonstrate neuroendocrine cells of the hamster and rat lung. The modified Eaton-Fedde procedure is the most efficient method of observing these cells, and is also the easiest to perform. With this method, the normal hamster lung contains a total of 2.00 x 10(-1) to 3.00 x 10(-1) neuroendocrine cells/mm in the small and large bronchioles. In the larger airways approximately 3.51 x 10(-1) neuroepithelial bodies (NEB)/mm are observed. Immediately after 24-hour exposure to NO2 the number of APUD cells dropped to approximately 25% of the control levels. These cells were decreased to 50% of the control levels throughout the 28 days of exposure. The number of NEB decreased transiently after 24 hours of NO2 but returned to normal numbers by day 14. We recommend the application of fluorescence techniques coupled with standardised sections and quantitative methods of study for analysis of APUD cells and NEB.