Abstract
1. In the present experiment, rabbits received 2-12mg/kg of Parathion dividing them into 4 groups by the difference of dosage and histopathological investigations were made on the changes produced in the lungs by 3 different stages of acute, subacute and chronic covering a period of more than 200 days.
2. Alveolar atelectasis was found to advance in parallel with the quantitative increase in its true findings and the intensity of those changes was enforced by the participation of a chronological factor which showed an ascending curve from the time of acute stage to the chronic stage. It should be emphasized, moreover, that this alveolar atelectasis shows an interesting association with the organization of the alveolar septum.
3. Appearance of the exudate into the alveolar septum (stem) was observed with its loosening. And, the inhibition of ChE by Parathion invites the accumulation of Ach which is considered to enhance vascular permeability. This inference is confirmed by the presence of hemorrhage in the same locality.
4. Tissue reactive changes observed on the alveolar septum (stem) to the interalveolar portion indicate the damages of the various elements of pulmonary tissues caused by Parathion intoxication. Proliferation of the mesenchymal cells in the same locality appears to indicate the tendency for fibrosis following the elapse of time.
