Segregation of blood groups in progeny of chimeric bulls born after transfer of aggregates constructed from 1/16-blastomeres of different genetic origin

Bovine 16-cell embryos of different genetic origin were disaggregated into individual 1/16-blastomeres and these were used for the construction of chi meric aggregates containing 14 blastomeres. Chimer as were produced from tw o embryos obtained from different parent pairs. Three chimeric bulls were b urn after nonsurgical transfer of 5 aggregates (iri vitro cultured for 24 t o 28 hours to compacted morulae) into 5 recipients. The blood group antigen s of the A, B, C, FV, J, M, S, Z, R', T' systems were determined in the chi meric bulls and in their offspring. Erythrocyte mosaicism was demonstrated in the chimeras in B and C systems. Hemolytic reactions were incomplete ind icating the existence of more than one population of red blood cells. The e xpression of antigens in chimeric bulls was different from that transmitted to progeny. The segregation of paternal antigens in offspring indicated th at chimeric bulls transmitted the genotype of only one parental pair. The c himerism of the three bulls from aggregated embryos has similar characteris tics as those in ordinary chimeric cattle twins.