Single-cell transcriptomic profiling of Hulunbuir short-tailed sheep and Hu sheep embryos at E16 and E19 reveals T gene mutation-mediated regulatory mechanisms underlying tail length phenotype

We profiled embryos at two critical developmental timepoints—16 and 19 days post-insemination—to investigate the cellular heterogeneity and molecular mechanisms underlying tail length dimorphism.

Our analysis identified 12–15 distinct cell types across samples and revealed MDK_ITGA6+ITGB1 as a central ligand-receptor pair in intercellular communication. We observed that HSTS embryos exhibit premature degeneration of the apical ectodermal ridge (AER), driven by a loss-of-function mutation in the T gene (c.G334T), which dysregulates BMP and FGF signaling pathways. Functional validation in a T mutant mouse model confirmed the role of this mutation in tail shortening.