Metabolic and cellular physiological differences between embryonic breast and leg muscle satellite cells in chickens

This study aimed to compare the anatomical characteristics of embryonic chicken muscle satellite cells ( CMSCs ) derived from breast and leg muscles of 18-day-old embryos. We analyzed the cellular behaviors related to proliferation, metabolism, and differentiation capacity. Breast-derived CMSCs exhibited significantly higher proliferation rates and accelerated cell cycle progression, as evidenced by a higher S phase distribution and lower G2/M phase distribution compared to leg-derived CMSCs. In addition, immunofluorescence staining for myogenic regulatory factors revealed that breast-derived CMSCs exhibited higher expression levels of paired box protein 7 ( PAX7 ), consistent with elevated PAX7 and myogenic differentiation 1 ( MYOD ) mRNA expression compared with leg-derived CMSCs. In contrast, leg-derived CMSCs showed significantly higher expression of myogenin ( MYOG ). Moreover, leg-derived CMSCs exhibited significantly higher mitochondrial respiratory activity indices, including oxygen consumption rate and basal respiration. In differentiation capacity analysis, the leg-derived CMSCs formed structurally more developed myotubes, and the expression of muscle-specific genes ( MYOD, MYOG, MYH1E, MYH7, TNNI1, TNNI2 ) was also significantly higher. These findings suggest that breast-derived CMSCs exhibit superior proliferative capacity, while leg-derived CMSCs possess enhanced myogenic differentiation potential, as supported by their increased oxidative phosphorylation activity and elevated expression of differentiation-related markers. In conclusion, the anatomical origin of CMSCs significantly influences their proliferative and differentiation capacities as well as their metabolic properties, providing a valuable basis for selecting optimal cell sources for cultured meat production and meat quality improvement.