DIFFERENCES IN THE MAMMARY RESPONSE TO ESTRONE AND PROGESTERONE IN CASTRATE MALE MICE OF SEVERAL STRAINS AND HYBRIDS

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Abstract
Castrate male mice of strains C3H/HeCRGL, A/HeCRGL, C57B1/CRGL, and BALB/c/CRGL, and of the reciprocal hybrids of C3H and C57B1 and of A and BALB/c, as well as mice of the C3H strain freed of the mammary tumor agent (C3Hd), were treated with 5 [mu]g estrone and 2 mg progesterone on alternate days for periods up to 85 days, to produce appreciable lobulo-alveolar development. Mammary glands were evaluated with regard to general growth (based on area measurements of the third pair of glands) and to degree of alveolar proliferation. The one strain (C57B1) which possesses neither genetic susceptibility to mammary tumor formation nor the mammary tumor agent shows the least alveolar response to the hormonal combination used. Within these strains and hybrids, the mammary tumor agent appears to influence the extent of alveolar development under hormonal treatment, but shows little relation to overall gland growth. After 85 days of treatment hyper-plastic nodules are seen in mice of the C3H strain and of the C3HxC57Bl hybrid.