Castration Effects of the Inherited Hormonal Influence

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Abstract
[female] mice of the high cancerous A and Z stocks were castrated at 4 wks. of age. Vaginal smears were made at 6-wk. intervals to observe hormonal stimula- tion. There was also a 2-wk. period of daily observation of the vaginal response of the castrate mice and of comparable groups of normal virgin animals. The vaginal orifice of Z castrates and hybrids was open 2 wks. after ovariectomy. Some mice were in estrous 5 mos. after castration. The first animal to develop a tumor was 7 mos. old. In the A strain, estrous cycles did not occur in the castrates and the vaginal pore rarely opened before 6 mos. Their uteri were small and the adrenals normal. In the Z and hybrid mice these organs underwent hyperplasia. Precancrous nodules and spontanous mammary cancer were observed in Z stocks and in those hybrids with the milk agent. No lesions occurred in the A strain. There is a relation between the incidence of breast tumors in mice and the degree of hormonal stimulation.