Effect of Petroleum Ether Extract of Mouse Carcasses as Solvent in Production of Sarcoma. ∗

Abstract

The production of sarcomata in mice may be influenced by the solvent used for the carcinogenic hydrocarbon. 1 Most experiments have been carried out with vegetable oils, lard, cholesterol or paraffin which are effective vehicles for 1:2:5:6-dibenzanthracene, 3:4-benzpyrene and methylcholanthrene. The increase in the incidence of skin tumors in mice following the application of mouse fat to the skin before tarring, as reported by Watson and Mellanby, 2 led us to investigate the effect of a petroleum ether extract of mouse tissues as a solvent for 3:4-benzpyrene in the production of connective tissue sarcoma.

The extract was prepared by refluxing fresh minced mouse carcasses, from which the stomach and intestines had been excised, with petroleum ether (maximum boiling point 50°C) for 16 hours. The petroleum ether was removed by distillation under reduced pressure. The resulting mixture was turbid, yellow and oily at 37°C. A gray-white, greasy, amorphous precipitate formed on cooling. The whole extract consisted largely of neutral fats and free fatty acids.

Sesame oil and colloidal solutions of 3:4-benzpyrene were also used. The colloidal material was prepared by the gelatin method of Boyland. 3 Each injection, representing 0.25 mg benzpyrene, was made in the subcutaneous tissues.

Three groups of 50 C57 black mice received a single injection of 3:4-benzpyrene in the inguinal region dissolved in sesame oil, petroleum ether extract of mouse carcasses or as a colloidal solution. In a fourth group of 50 mice, each animal received a single injection of each of the 3 solutions. All of the mice were obtained from the Roscoe B. Jackson Memorial Laboratory and were 5 to 6 weeks old when the injections were made. They were observed once weekly. The time when a progressively growing mass was first noted was taken as the appearance time of the tumor.