Failure to Transmit Carcinogenic Agents from the Pregnant Mouse Embryos in utero

Abstract

Several investigators have reported transmission in mice of carcinogenic agents from mother to embryo. One group of such investigators believes that a mash of embryos which have developed in the body of a cancerous mother, can transmit cancer on transplantation in other mice. A diagram of this type of relationship is given in Fig. 1.

It is evident that if a highly specific and effective degree of carcinogenic activity were transmitted in the way described it would be definite proof of the existence of such an agent smaller than and separable from the cell. Since the larger mass of evidence in rodent tumors argues against the probability that such a condition exists, it seemed worth while to make certain experiments along this line.

As far as possible the technique described by Tesauro 1 was followed.

In any mice which showed masses at the site of transplanted embryonic tissue, observations by palpation were made at frequent intervals. The size of masses was indicated by an outline of their approximate area recorded on a chart kept for each animal. In each case histological preparations were made of the masses which persisted. Study of these preparations showed the masses were either teratoid or inflammatory in nature. In no case did a mass resemble the original tumor employed. Similar inflammatory or teratoid growths were obtained in many control animals inoculated with an emulsion of embryo from non-cancerous mothers. The results of the various experiments are given, in a condensed form in Table I. In no case was a malignant tumor obtained in either experimental or control animals, as a result of inoculation with embryonic tissue.

Although negative results are never entirely satisfactory it seemed worth while to record the fact that the results obtained by Tesauro are not universally applicable and that the principle which is involved remains, in so far as our experience is concerned, unestablished.