Changes in cell number and lung morphology during early postpneumonectomy lung growth

We studied early postpneumonectomy lung growth in adult rats with the aim of determining which lung cells and tissues were involved and what the magnitude of the changes was. Ultrastructural stereological-morphometric measurements were performed 7 days after left pneumonectomy; lung weight, DNA, and protein were also measured. Relative to sham controls, the number of type 2 epithelial cells per right lung increased 34% and the number of capillary endothelial cells increased 28%. The total type 1 epithelial cell volume and surface area both increased 26%, and the total volume and luminal surface area of the capillary endothelial cells increased 24 and 22%, respectively. The number of interstitial cells did not change significantly. The total number of lung cells in the alveolar region was increased 22%; this correlated with a 26% increase in right lung DNA content. We conclude that the main changes during early postpneumonectomy lung growth are increases in the number of type 2 epithelial cells and capillary endothelial cells and in the total capillary and alveolar epithelial surface area.