An ultrastructural morphometric analysis of bronchial secretory cells was carried out on hamsters treated intratracheally with 300 micrograms of human neutrophil elastase (HNE) in 0.5 ml saline, saline alone, or left untreated. Five to 6 animals were killed at 2 h and at 3, 8, and 16 days after treatment. Electron micrographs were prepared from the hilar region of the left main intrapulmonary airway; 125 +/- 16 (mean +/- SE) granulated secretory cells extending from basement membrane to lumen were analyzed for each group. The number (Ng) and area (Ag) of granular profiles per cell, the area of cell profiles (Ac), and the volume density of secretory granules per cell (Vv) were determined using an electronic image analyzer. There were significant decreases in Ng, mean Ag, and Vv in the 2-h HNE group when compared with the saline group. Values of Ng, mean Ag, and Vv were similar for HNE and saline groups at 3 days, but were significantly increased at 8 and 16 days. The Ac of HNE-treated groups was similar to their saline control groups at all time points except at 16 days when the HNE-treated group enlarged to double that of its saline control group. An ultrastructural differential cell count showed a decrease in frequency of granulated secretory cells at 2 h and an increase at 8 and 16 days; there was an inverse change in the frequency of nongranulated secretory cells at these times. The proportion of ciliated, preciliated, and indeterminate cells remained constant over time in all treatment groups.(ABSTRACT TRUNCATED AT 250 WORDS)