Mitochondrial lamellated bodies and surfactant depots in the Type II cells of the lung compared by bimetallic staining and X-ray analysis.

After heavy dosages of sensory irritants osmiophilic whorls (mitochondrial lamellated bodies) are found in the mitochondria of the Type II cells of the lung. To obtain evidence of their nature, the lead/osmium (Pb/Os) ratio in these and other bodies after bimetallic staining was studied by electron probe X-ray analysis during transmission electron microscopy. To allow for inter-specimen variation the Pb/Os ratio was divided by the Pb/Os ratio for chromatin in the same cell, to give a "relative ratio". The values of the latter ranged from 1.4 for granules in an eosinophil leucocyte to 0.60-0.77 for lamellated osmiophilic bodies of Type II cells, 0.4 for nerve myelin, and 0.05 for fat globules. The Pb/Os ratio for mitochondrial lamellated bodies did not differ significantly from that for lamellated osmiophilic bodies (which are depots of lung surfactant) in the same cell. This is compatible with the mitochondrial lamellated bodies consisting of excess surfactant produced in response to stress. the method is capable of extension.