Production of Mammary Carcinomas in Male Mice With a Single Implantation of Oestrone

Lacassagne 1 produced tumors in male mice of the R III strain, in which 70% of the females develop spontaneous mammary carcinomas, by the weekly injection of 300 I.U. of oestrone benzoate in oil. The tumors were found to develop sooner in males so treated than they occur spontaneously in females of the same strain. These findings have been repeated by Burrows, 2 by Bonser, 3 by Cramer and Horning, 4 and by Gardner, Smith, Allen and Strong. 5 Lacassagne 6 used oestrone, oestradiol, equiline, and equilinine, all hormones being injected weekly in oily solution. Burrows painted his animals twice weekly with oestrone, .01% in benzene; Bonser used oestrone benzoate in olive oil as did Gardner, et al., while Cramer and Horning used oestrone in chloroform applied to the skin twice weekly.

Recently Deanesly and Parkes 7 have shown that prolonged effects may be obtained by the implantation of crystals of oestrone under the skin. A capon so treated with a 3 mg crystal of oestrone maintained the hen coloration of the breast feathers for over 3 months. It seemed that this method might be made use of to repeat the experiments of Lacassagne while decreasing the labor of weekly injections and removing any confusing results due to the application of such large quantities of solvent.

In order to determine whether prolonged action of oestrone could be obtained in mice by the implantation of oestrone crystals 7 stock females were selected and vaginal smears taken for a week to show that they were all ovulating normally. At the end of this time crystals of oestrone (obtained from the Schering Corporation through the kindness of Dr. Schwenk) weighing 0.68 mg to 1.06 mg recrystallized from ethyl alcohol were introduced beneath the skin of the abdomen of each animal with a trocar.