Abstract: To establish a preliminary procedure for making interspecific chimeras between cattle and buffalo by Aggregating Blastomeres Method. Chimeric embryos were reconstructed by aggregating blastomeres from early bovine and buffalo embryos isolated by either enzymatic or mechanical method in a droplet of culture medium containing 100 μg/ml phytohemagglutinin （PHA）. Aggregating buffalo morulae with bovine embryos at either 8-cell or blastula stage did not differ significantly in their aggregation rate （85.7% vs 77.8%, P>0.05） and proportion developing to blastocysts （72.2% vs 42%; P>0.05）. There were also no significant difference in aggregation rate （92.3% vs 86.7%, P>0.05） and blastocyst development （58.3% vs 46.2%; P>0.05） between the chimeric embryos derived from 8-cell embryonic blastomeres isolated by 0.25% Pronase and microsurgery. In conclusions,①The aggregation rate and embryonic development of chimeric embryos are not influenced by the stages of embryos to be aggregated; ②Methods for isolation of blastomeres （enzymatic treament and microsurgery） do not affect their aggregation rate and embryonic development.

Key words: cattle; buffalo; embryo aggregation; chimera