Clonality of urogenital organs as determined by analysis of chimeric mice

Though the first mammalian chimera was reported in 1961, suitable markers for different animal strains which are easily detectable in histological sections of all or most organs have not existed. Chimeric mice were produced having an excellent histological marker, the C3H antigen, which is strain-specific and fulfills all the criteria for an ideal strain-specific histological marker. Using male and female C3H-Balb/c chimeric mice we examined epithelial cells of urogenital organs and their morphological or functional units, such as the glomerulus, to determine whether individual organs and their morphological subunits were monoclonal or polyclonal in origin. We found that the epithelial parenchyma of most male and female urogenital organs (the prostate, seminal vesicle, epididymis, ovaries, vagina, kidney, ureter and bladder) and their morphological subdivisions were derived from cells of both input strains, indicating a polyclonal origin for each organ and/or organ component. A notable exception was the uterus in which all individual uterine glands examined (n = 403) were found to be either entirely Balb/c or entirely C3H, indicating a monoclonal origin. The clonality of urogenital structures is discussed in terms of the morphogenesis of the urogenital system.