Some Factors Involved in the Induction or Growth of Testicular Tumors in BALB/c Mice

Abstract

The effects of interruption of estrogen after second exposure to estrogenic stimulation, age of the animals, and treatment with progesterone were studied on the development and growth of interstitial-cell tumors of the testes in BALB/c mice implanted subcutaneously with diethylstilbestrol-cholesterol pellets. (1) Estrogenic stimulation for 8 weeks, removal of the pellet for 24 weeks, and reimplantation of a second pellet delayed the occurrence of tumors by approximately the intervening nonestrogen period, which indicated that the process was interrupted, but did not progress or regress to any appreciable extent during that period. (2) Diethylstilbestrol pellets implanted in mice from 2 weeks to 12 months of age showed that all age groups responded with the appearance of testicular tumors. The tumors appeared later and reached a lower cumulative frequency in the 2-week-old mice, and a smaller proportion grew progressively after removal of diethylstilbestrol from the 12-month-old mice. (3) Progesterone retarded but did not prevent the occurrence of estrogen-induced tumors under the conditions of the experiment.