Embryo-Arsenic Tumors in Rats

Abstract

Carrell 1 by the injection of chick embryo pulp in conjunction with dilute arsenious acid obtained in fowls a tumor of sarcomatous type. The result was the same whether the embryo was mixed before injection with the arsenious acid or the two injected simultaneously at different places. White 2 repeated these experiments and confirmed the results. Askanazy 3 transplanted rat embryo into grown rats and added Fowler's solution to their drinking water. In each of 2 series in which arsenic was used one rat was found to have a tumor of a malignant character. In one, the examination was made 13 and in the other 15 months after the embryo transplant. In the experiments of Carrell and of White the tumors developed as early as the ninth day and rather frequently in the fowls receiving the injections. From the results obtained in these investigations it appears that the response in the rat as compared with fowls is slower and less certain. The aim of our experiments was the investigation in rats of some of the variable factors, especially sites of injection and ages of embryos, which might explain slow and uncertain results.

Experiment I. The usual procedure with minor variations has been to draw much of the embryo into a syringe fitted with a short needle having 1 mm. lumen and at once to draw dilute arsenious acid to the 2 cc. mark. Of this suspension 0.5 to 1 cc. was injected. The time elapsing from removal of living embryo to injection was under 5 minutes. One of us (McJunkin) injected the testicles of 7 rats with a suspension of 3 mm. embryos in 1-150,000 arsenious acid. Six weeks later there was found in the testicle of one rat a minute opaque focus which microscopically consisted chiefly of cysts filled with cornified material.