Quantitative studies of argyrophilic APUD cells in airways: II. The effects of transplacental diethylnitrosamine.

The effects of transplacental administration of diethylnitrosamine (DEN) on the densities of epithelial and APUD cells in the large and small airways of developing hamsters have been studied quantitatively. The APUD cells are quantitated by relating them to the number of airway epithelial cells; APUD cells are present in similar densities in the large airways (0.12 APUD cells/100 cells) and small airways (0.14) of 2-day-old control hamsters. At 4 days an increase in the densities of APUD cells and an increase in epithelial cells is observed in the small airways, whereas those in the large airways decrease slightly. At later periods there is a progressive decline in the density of APUD cells in the control hamsters. Exposure in utero to DEN results in a generalized increase in APUD cells in 2-day-old hamsters, which is more pronounced in bronchioles (fivefold increase). The effect disappears in older animals. It also results in a transient increase in tracheal epithelial cell density in 7-day-old hamsters. Whether the selective and transient APUD cell hyperplasia induced by transplacental administration of DEN results from proliferation of these cells or from differentiation of other types of epithelial cells into APUD cells requires further study.