Figure 2. Morphometric analysis of lungs from 8-wk-old animals. A and B) Histology of lung sections stained with modified Gill’s hematoxylin from 8-wk-old animals for conditionally targeted animals (B) and littermate controls (A). C and D) Computerized quantitative morphometric analysis of lung sections. Data are expressed as the mean chord length in micrometers (C) and airspace area in square micrometers (D) ± SD for conditionally targeted (solid bars) (n=12) and littermate control (open bars) (n=11) animals.