Effect of Hypophysectomy on Growth of the Walker Rat Tumor

Abstract

Since hypophysectomy is known to lead to cessation of body growth, it seemed interesting to investigate its effect upon the growth of a tumor such as the Walker rat tumor. Twelve out of 25 young albino rats bearing tumor transplants 8 to 12 days old were therefore hypophysectomized (by Doctor Hans Selye), the remainder being kept as controls. The area of the largest cross-section of the tumors was measured by sketching them upon squared paper with the aid of calliper measurements; the total weight of the rats was also followed. The results are summarized in Table I.

Hypophysectomy evidently retards but does not prevent the growth of the tumors; but the total weight of the rats and their tumors remained stationary (as in hypophysectomized rats without tumors) or slightly declined. With one exception, in which the growth-curve suggests that the operation was incomplete, the hypo-physectomized rats died in from 21 to 36 days, and in none of them did the tumor attain 50 gm. weight. In the unoperated rats the rate of increase of the size of the tumors was obviously greater, and the total weights increased. These rats were killed off at intervals as the experimental animals died; not one of them died, although in many cases the tumor exceeded 100 gm. in weight. It was noted that in the hypophysectomized rats, in the last few days of life, the total weight decreased; in more than half of the cases the size of the tumor also decreased before death.

The volume and weight of the tumors may be roughly estimated from the measured cross-sections, allowing for slighter development in the third dimension; this method has been checked in another series in which the tumors were weighed post mortem.