Clonality of urogenital organs as determined by analysis of chimeric mice

Though the first mammalian chimera was reported in 1961,suitable markers fo r different animal strains which are easily detectable in histological sect ions of all or most organs have not existed. Chimeric mice were produced ha ving an excellent histological marker, the C3H antigen, which is strain-spe cific and fulfills all the criteria for an ideal strain-specific histologic al marker. Using male and female C3H-Balb/c chimeric mice we examined epith elial cells of urogenital organs and their morphological or functional unit s, such as the glomerulus, to determine whether individual organs and their morphological subunits were monoclonal or polyclonal in origin. We found t hat the epithelial parenchyma of most male and female urogenital organs (th e prostate, seminal vesicle, epididymis, ovaries, vagina, kidney, ureter an d bladder) and their morphological subdivisions were derived from cells of both input strains, indicating a polyclonal origin for each organ and/or or gan component. A notable exception was the uterus in which all individual u terine 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 sys tem.