Thus, primary muscle SCs can serve as an excellent in vitro system for evaluating the various stages of muscle development. Little is known about the proliferative potential of SCs isolated from different pig breeds. Thus, this study was conducted with SCs isolated from Lantang and Landrace pigs to test the hypothesis that muscle fibers from different pig breeds have different proliferative abilities during the neonatal stage. In this study, Lantang and Landrace pigs were selected as neonates to validate the hypothesis that there was difference in the proliferative ability of SCs between different breed pigs during neonatal period. During postnatal growth, the increase in skeletal muscle mass is mainly due to increased muscle fiber Rebaudioside-D number and size. Postnatal fiber hypertrophy, which is associated with the accumulation of myonuclei and muscle-specific proteins, is correlated with the number of prenatally-formed muscle fibers. Furthermore, the number is fixed before birth, and fiber formation ceases at approximately 85�C90 days of gestation. This cessation corresponds to when the total number of fibers is established in pigs. Thus, the total number of muscle fibers is an important aspect of postnatal muscle growth. In this study, three muscle tissues were used to determine the differences in fiber number and CSA in Langtang and Landrace pigs. Based on morphologic analyses, the fiber numbers in the three muscle tissues from Lantang pigs were significantly higher, while the CSA was significantly lower than from Landrace pigs. There are a few studies comparing muscle fiber number and CSA between different pig breeds. Staun showed that fiber number in LD muscle in Pie��train pigs was lower and CSA was higher than in Danish Landrace pigs. The same results were found when muscle fiber number and CSA were compared between two different animals. In that report, the pig LD muscle shows a higher fiber number and lower CSA compared with the extensor digitorum Epimedin-B longus muscle of the mouse. Our data are similar to studies by Staun and Rehfeldt. Previous studies indicated that muscle fiber number and muscle crosssectional area had a profound influence on meat quality traits.