This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Bittner, J. J. Search for Related Content PubMed Articles by Bittner, J. J.

Assay of Spontaneous and Transplanted Mammary Tumors for the Mammary Tumor Agent^*

( Division of Cancer Biology, Department of Physiology, University of Minnesota Medical School, Minneapolis 14, Minn.)

In biological assays on the tumor-producing ability of the mammary tumor agent, considerable variation was observed in the activity of several spontaneous mammary tumors from the same inbred stock, including those from litter-mates.

The results could not be correlated with either the source of the mammary tumor agent or the time of development of the tumors.

Extracts of three transplanted tumors were as active after one passage, and in some cases ten, as the original spontaneous tumor.

A decrease in the activity of one transplanted tumor was seen in the eighteenth passage, and it was not restored in later passages except when extracts of high concentrations were administered.

The mammary tumor agent survived for as long as the tumors were transplanted—namely, ten and 30 passages.

Spontaneous mammary cancer proved to be a better source of the mammary tumor agent than did either spleen or liver from the cancerous donor.

In one study, it is probable that the mammary tumor agent could not be demonstrated in the liver and spleen from donors bearing transplanted tumors, although the tumors were very active.

For some experiments, transplanted mammary cancer may be the most satisfactory source of the mammary tumor agent.

^* Assisted by grants from the American Cancer Society upon recommendation of the Committee on Growth of the National Research Council, the National Cancer Institute of the National Institute of Health, U.S. Public Health Service, and the Graduate School Cancer Research Fund of the University of Minnesota.

Received 12/ 3/52.