Abstract
In order to cause hemolysis, 0.5 ml/kg of phenylhydrazine was injected subcutaneously into rabbits every three days at a concentration of 2%, 4% and 8%, respectively. They were divided into acute, subacute and chronic groups according to the hematological changes. The rabbits were then sacrified and the thyroid glands were examined histologically.
1. Hematological findings: There was an acute drop in both red blood cells and hemoglobin right after administration of phenylhydrazine, while, on the contrary a marked increase in number of reticulocytes was noted.
2. Histological findings of thyroids :
a. Acute group: Mild dilatation of veins, congestion and edema were found in the interstitial tissue. The parenchyma showed conspicuous degeneration of follicular epithelia, desquamation, destruction and necrosis.
b. Subacute group: The interstitium demonstrated marked changes following circulatory disturbance and mild fibrosis. The parencyma became atrophic, and there were figures of change in amount of colloid.
c. Chronic group: Fibrotic changes were more remarkable than the subacute group. The parenchyma revealed diffuse atrophy of follicles and disappearance of colloid.
3. The above findings suggest that degenerative changes were induced by hypoxia following hemolytic anemia. There is also a possibility of the toxicity of phenylhyrazine causing degeneration of follicular epithelia.
