INCOMPLETE DEVELOPMENT OF THE SPLEEN AND THE DEFORMITY IN THE CHIMERAS BETWEEN ASPLENIC MUTANT (DOMINANT HEMIMELIA) AND NORMAL MICE

The semidominant gene Dh (Dominant hemimelia) induces skeletal and vis ceral abnormalities of various degrees and failure of the spleen in mi ce. The homozygous individual (Dh/Dh) seems to be lethal. The present experiment was designed to investigate the ability Dh cells to form a spleen and the genesis of the hind limb malformations by Dh/Dh and Dh/ + cells in chimeric mice. The Dh/Dh and Dh/+ embryos were produced in the F-2 progeny of a cross between inbred strains of Dh/+ and DDD mice . They were aggregated with C3H/He or C57BL/6 embryos to make chimeras . identification of Dh/Dh or Dh/+ embryos was carried out by Pep-3, an d chimerism was analyzed by Gpi-1. Of 25 chimeras carrying the Dh gene , four mice formed a small spleen, two mice had a vestigial spleen, an d the others no spleen. The tissues of the incompletely developed sple ens were normal histologically and Dh cells were involved in the tissu es of the spleen. In the chimeric mice, hindlimb malformation by the D h gene was reduced in severity and the lethality of the homozygote (Dh /Dh) was rescued. (C) 1995 Wiley-Liss, Inc.