ABSTRACT: Skeletal muscle satellite cells (SMSCs) are central to embryonic myogenesis and post-natal muscle regeneration; however, their heterogeneity and transcriptional dynamic during avian embryogenesis remain largely unexplored. Here, we employed single cell RNA sequencing (scRNA seq) on 42,886 SMSCs isolated from goose leg muscles at four embryonic stages (E13, E15, E18, and E23). Unbiased clustering identified 22 distinct clusters, classified into six main cell types: satellite cells (PAX7+MYF5+NRXN1+), myo-cytes (MYOD1+MYOG+ACTC+), fibro adipogenic progenitors (FAPs, DCN+CDH115+COL6A3+), endothelial cells (CDH5+KDR+PECAM1+), immune cells (CD82+PTPRC5+FCER1G+), and Schwann cells (GPX3+SNCA+SKAP1+). Satellite cells rep-resented the predominant population and were further subdivided into quiescent (PAX7+), activated (PAX7+MYF5+), and proliferative/differentiating (MYF5+MYOD1+) states. Differential expression analysis revealed 2,603 genes dynamically regulated in satellite cells across developmental stages, including core regulators of stemness (PAX7), commitment (MYOD1), and differentiation (MYOG), as well as genes implicated in sarcomeric and cytoskeletal remodeling. Additionally, 517 genes were universally ex-pressed across all satellite cell states, emcompassing ACTA2, TPM1, CDK1, CCND3, FGF2, MET, MYF5 and RUNX2. Pseudotime trajectory analysis delineated a linear pro-gression from quiescent to activated and subsequently to proliferative/differentiating states, characterized by dynamic activity in Wnt, TGF β, BMP, Notch, PI3K/AKT, and MAPK pathways. Cell cell communication analysis demonstrated robust intercellular signaling networks in quiescent cells, which diminished with activation and differenti-ation, involving FGFR, Ephrin, Collagen, and CADM signaling families. Together, this work establishes a comprehensive single cell atlas of goose SMSC development, re-vealing subpopulation heterogeneity, state specific molecular signatures, and key sig-naling pathways underlying myogenic progression. Our findings advance the under-standing of avian skeletal muscle development and provide valuable resources for en-hancing muscle traits in poultry.
