Previous studies of acute exposures of rats and other mammals to ozone demonstrated severe pulmonary parenchymal lesions in the central region of the pulmonary acinus and extensive edema. In this study, an adult Rhesus monkey was exposed to 4 ppm ozone for 4 hours and euthanized immediately after the exposure. A control Rhesus monkey was also euthanized. The lungs were fixed via the trachea at 30 cm of water pressure with Karnovsky's fixative. Tissue was selected from acini of the right diaphragmatic lobes. Much of the selected tissue in the exposed primate was edematou.s. Tissue blocks (1mm2 × 2mm) were immersed in a cryoprotective agent (25% glycerol/0.2 M cacodylate buffer) for 2 hours, mounted in apposed specimen holders, and rapidly frozen in Freon 22 (cooled in liquid nitrogen).
