Proliferation of alveolar type II epithelial cells in residual lungs following thoracotomy.

We have found that the number of alveolar type II epithelial cells was markedly increased in the alveolar walls along with the visceral pleura of an excised residual lung in patients who had undergone an exploratory thoracotomy with partial lobectomy seven or nine days prior to the second thoracotomy with resection of the residual lung. Such increase in proliferation of alveolar type II epithelial cells was not found in the excised lung not exposed to a prior thoracotomy, and not in the excised lung exposed to a prior thoracotomy more than 1 year before the second thoracotomy. These findings suggested that remodelling of the alveolar epithelial cells occurred in the residual lung in the early period following thoracotomy.