[Effect of chalones on changes in the rat larynx induced by DMBA]

The experiments used 144 non-inbred albino male rats aged 2-3 months. They were divided in 6 study groups and one control group. The animals of groups 1-3 received 0.01 ml infusions of 6.5% solution of DMBA into the larynx twice a week for 6 months. In groups 4-5, animals were treated with acetone and dimethylsulfoxide, respectively. Epidermal chalones were instilled in group 2 1 hr after DMBA infusion, and hepatic ones--in group 3. After 7 and 10 months, the animals were sacrificed with large doses of ether, 6 sections were taken from each larynx and stained with hematoxylin--eosin. The statistically treated results showed chalone treatment to inhibit the development of precancerous lesions in larynx induced by DMBA. The greatest inhibitory effect was registered in epidermal chalone treatment.