S. M. Lee*, Y. H. Jeoung*, S. H. Hwang*, H. Y. Park*, D. H. Yoon**, S. J. Moon*E. R. Chung*** and M. J. Kang*Department of Animal Science, Insti. of Ag. Sci. and Tech., College of Agriculture & Life Science,Chonnam National University, Gwangju 500-757, Korea*, National Livestock Research Institute, RDA**Department of Biotechnology, College of Life Science and Natural Resources, Sangji University***ABSTRACTThe development of marbling in cattle is closely associated with an increase in adipocyte size andnumber within muscle. The adipose precursor cells have the capacity to differentiate into adipocytes withinthe muscle during the formation of marbling. In this studies, we established the cell culture system fordifferentiation of intramuscular preadipocyte isolated from the sirloin of Hanwoo aged 12 months. Theintramuscular preadipocyte cells exhibited a fibroblastic appearance and differentiated into adipocytes bytreating confluent cells with differentiation medium containing insulin, dexamethasone, and troglitazone.When intramuscular preadipocyte cells were differentiated at 18 day, the triglyceride concentration washigher than control cells. Moreover, the thiazolidinedione treatment increased adipogenesis. RT-PCR analysisconfirmed the significant expression of PPAR mRNA during adγ ipocyte differentiation. In conclution, ourculture system used in this study allowed intramuscular preadipocyte cells to differentiated into adipocytesand intramuscular preadipocyte cells may be useful in the further study of differentiation mechanism ofadipocytes in Hanwoo.(Key words : Primary culture, Bovine, Thiazolidinedione, Peroxisom proliferator-activated receptor- ,γPreadipocyte)