Peroxisome proliferator-activated receptor (PPARy) is a transcription factor that regulates adipogenic genes and preadipocyte factor-1 (pref-1) is a transmembrane protein that regulates preadipocyte differnetiation. The role of PPARy was investigated using reverse transcription polymerase chain reaction (RT-PCR) by measuring PPARy mRNA levels in bovine adipose depots and longissimus dorsi muscle. No significant differences in PPARy mRNA levels were observed between 10 Charolais and 10 Holstein cattle for either tissue. Differences were observed between depots within these breeds. Correlations were performed among PPARy, carcass characteristics, and adipogenic genes. Pref-1 antibodies were used to immunolocate preadipocytes in bovine muscle tissue to the perimycium, near fat cells and blood vessels. The preadipocytes may exist in muscle tissue for short periods of time or may arise from a source external to the muscle. A computer image analysis program was developed for the quanitifaction and characterization of intramuscular fat in whole muscle tissues. / xvi, 154 leaves : ill. (some col.) ; 28 cm.