Pulmonary Alveolar Cell Inclusions: Their Development in the Rat

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Science  11 Sep 1964:
Vol. 145, Issue 3637, pp. 1192-1193
DOI: 10.1126/science.145.3637.1192


Cytoplasmic inclusions in the special pulmonary alveolar cells of adult, newborn, and fetal rats were investigated by electron microscopy and histochemistry, and lung extracts were analyzed for surface-tension activity. The inclusions were positive in the periodic acid-Schiff test after digestion with diastase and were not stained with toluidine blue; they formed myelin figures and possessed alkaline phosphatase activity. Both the typical surface tension activity and the inclusions developed 2 days before birth. These properties differentiated the inclusions from mitochondria.