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Strain difference in the expression of mammary tumor virus antigen in the male genital organs of mice during aging.

Mammary tumor virus (MTV) antigen expression was tested in the male genital organs (testis, epididymis, prostate, seminal vesicle and coagulating gland) of DD/Tbr, KF and DDD strains (dd (German) mouse group), GR strain (Swiss origin), SHN and SLN strains (different Swiss origin), C3H and A strains (American origin), BALB/c and C57BL strains (low mammary tumor strains), and DDf and SHNf strains (MTV eliminated strains). Microimmunodiffusion analysis showed that expression of MTV antigen is tissue extracts was found most frequently in the prostate, sometimes in the seminal vesicle and coagulating gland but rarely in the epididymis and not at all in the testis of mammary cancer strains. No expression was found in these organs from BALB/c and C57BL strains. The earliest expression was found in GR, SHN and SLN strains of Swiss origin. Expression was not lost in SHNf strain, indicating that it is due to genetically transmitted MTV, rather than a milk-factor. Male genital organs from two mammary cancer strains of American origin became positive occasionally at rather higher age than in the strains of Swiss origin. DD/Tbr, KF and DDD strains expressed MTV antigen in the male genital organs at intermediate age between the strains of Swiss origin and American origin. Complete disappearance of MTV antigen expression in these organs of DDf strain indicates that the expression of MTV in DD/Tbr is due to a milk-factor.