Study on the spatiotemporal development of skeletal muscle in embryonic Pekin ducks

This study aimed to investigate the developmental patterns of breast muscle and leg muscle in embryonic Pekin ducks, and to screen potential genes regulating their independent development and growth differences. Muscle weight and histological characteristics were measured at eight embryonic stages (E11, E13, E15, E17, E19, E21, E23, E25; n=10). Transcriptome analysis was performed on breast muscle at E11, E13, E17, and E21, and on leg muscle at E17 and E21. The results showed that breast muscle weight exhibited an S-shaped growth pattern, while leg muscle weight increased significantly in a linear or quadratic trend with increasing embryonic age ( P < 0.0001). Histological features indicated that mature myofibers appeared in leg muscle at E19, but were not observed in breast muscle until E23. KEGG enrichment analysis of differentially expressed genes showed that pathways such as cytoskeleton in muscle cells and oxidative phosphorylation were involved in skeletal muscle development. Using bioinformatics analyses including WGCNA and Mfuzz clustering, we screened 5 potential genes regulating breast muscle development (including MYOD1 ), 12 potential genes associated with leg muscle development (including SDHA ), and 11 potential genes mediating the developmental differences between breast and leg muscle (including PDHA1 ). Notably, from E21 to E25, leg muscle maintained rapid development whereas breast muscle development entered a plateau phase, and this difference may be driven by genes related to energy metabolism. This study systematically clarified the developmental patterns of breast muscle and leg muscle in embryonic Pekin ducks, providing a basis for further dissecting the molecular mechanisms underlying the spatiotemporal development of avian skeletal muscle.