Single-cell atlas of the developing mouse oviduct reveals smooth muscle heterogeneity and identifies Vps34 as a critical regulator of female fertility

Abstract

The oviduct smooth muscle layer is traditionally regarded as a contractile unit. Limited understanding exists regarding the molecular heterogeneity and intercellular communication during development timeline, which is critical for female reproductive function. To address this, we performed single-cell RNA sequencing (scRNA-seq) to profile the cellular composition of mice oviducts at four developmental stages: neonatal (7 days), pre-pubertal (3 weeks), young adult (8 weeks) and middle-aged (9 months). We aim to provide a framework for further investigation of oviduct biology and associated reproductive disorders. We delineate three distinct (SMC) subtypes, with their relative proportions shifting dynamically across the developmental timeline. SMC1 represented a transient progenitor population exclusive to neonatal oviducts. SMC2 displayed a mature contractile phenotype, while SMC3 uniquely expressed hormone-responsive genes (Esr1, Pgr) and showed enrichment of autophagy-related pathways. Functional studies demonstrated that SMC-specific deletion of Vps34 disrupts oviduct coiling and muscular integrity, leading to vacuolar degeneration and a significant reduction in litter size in mice. Additionally, we map five ciliated and six secretory epithelial subtypes and suggest that FN1 signaling may serve as a potential mediator of crosstalk between epithelial and SMCs during development, with the FN1-SDC4 axis emerging as the dominant interaction in mature oviducts. Thus, while the contractile and hormone-responsive functions of the oviductal muscle layer have long been recognized, our work provides its underlying cellular complexity during development. Our study constructs a developmental atlas of murine oviduct SMCs, revealing that the myosalpinx is composed of functionally distinct SMC subtypes with dynamic developmental trajectories. The identification of Vps34 as a critical guardian of myosalpinx integrity offers a new cellular framework for understanding human tubal pathologies. These findings highlight the importance of SMC subtype homeostasis and autophagy-mediated maintenance of myosalpinx structure, providing a basis for future mechanistic studies on oviduct function and dysfunction.