ELECTRON-CYTOCHEMICAL STUDIES ON THE DIFFERENTIATION OF MOUSE LUNG ALVEOLAR EPITHELIAL CELLS WITH SPECIAL REFERENCE TO CHANGES IN MITOCHONDRIA

Abstract

Changes in mitochondrial structures and cytochrome oxidase activities were electron-cytochemically observed in lungs of butylated hydroxytoluene (BHT)-administered mice. The cytochrome oxidase activity was demonstrated by the diaminobenzidine method, and changes in the mitochondrial sizes during the differentiation were measured by morphometric analysis.
BHT selectively damaged Type I cells, and then Type II cells differentiated to Type I cells. When Type II cells differentiated to Type I cells, the mitochondria were greatly reduced in size and number. The mitochondria in intermediate cells became slender and divided into smaller mitochondria. It is possible that the amount of cytochrome oxidase per mitochondrion decreased. Thus, these cytochemical approaches evidenced functional as well as ultrastructural changes that occurred during the alveolar differentiation.