Temperature Level and the Growth of Embryo and Tumor of Tumor-Bearing Eggs

The technique of growing tumor tissue in embryonated eggs has been routine in this laboratory for more than 4 years. The use of the yolk sac method of inoculation has made it comparatively simple to maintain rat and mouse tumors indefinitely by egg to egg inoculations. 1 , 2

The size of the tumors grown in this manner were of the same order as those obtained by transplant in the host animal. This continued to be so after as much as 114 transplant-generations or about 4 years continuously in eggs. Apparently the egg environment satisfies all the requirements of malignant tissue for vigorous growth.

The inoculation of eggs through the yolk sac results in tumor implantation on the yolk sac inner wall. 3 In this situation the growth of the tumor presents a minimum of interference with the development of the chick embryo. Tumor tissue and chick tissue grow together sharing a common blood supply. It is not uncommon for the egg-grown tumor to weigh as much as 6 g at the 17 th day of egg incubation, while the chick embyro normally weighing about 20 g at this stage is reduced to 10 or 12 g.

The egg environment is relatively stable but a certain amount of manipulation will be tolerated by the chick embryo. This is especially so with respect to temperature. Incubating eggs will withstand considerable variation in temperature and still survive to the 17-18 day period.

The present paper is concerned with a study of the comparative reactions of tumor and chick tissues grown together to temperatures above and below that required for normal incubation.

Experimental. Embryonated eggs on the 4th day of incubation were inoculated with dba mouse mammary carcinoma. The eggs of one series of inoculations were divided into 3 groups and incubated from the time of implantation until the termination of the experiment at 3 different temperatures. One group representing the control was kept at 99-100° F, a second group was incubated at 96-97°F, and the third group was maintained at a temperature of 103-104°F. At the 18th day of incubation, or 14 days after tumor inoculation, the embryos and tumors of the surviving eggs were harvested and weighed.