Studies on the inherited susceptibility and inherited hormonal influence in the genesis of mammary cancer in mice.

Additional observations will be presented in this report on the development of mammary cancer in mice, especially virgin females, associated with the action of an inherited hormonal influence, termed the inherited hormonal influence. Comparisons will also be made for the genie make-up of the in herited susceptibility versus the inherited hor monal influence. While the role of the hormonal stimulation in the genesis of mammary cancer has been known for many years (see review by Loeb [26]), not until 1944 was it demonstrated that the genie control of the hormonal mechanism was related to the ap pearance of these tumors in virgin mice (15, 21). This was found by mating females of the A strain, where the incidence in virgin females was known to be low (6), with males of the Z or C3H stock, in which strain both the virgins and breeders have a high incidence. When the FI females were main tained as nonbreeders, a high incidence was noted. Thus, the hormonal mechanism which deter mined the high incidence in virgins of the Z strain was transmitted and called the inherited hormonal influence (9). In this cross, the females of the A strain con tributed the mammary tumor agent and the in herited susceptibility for mammary cancer, while the Z fathers transmitted the inherited hormonal influence, as well as the inherited susceptibility. The three primary factors (7) considered to be needed for a high incidence were represented. Further studies from this laboratory indicated