Single-nucleus RNA sequencing provides insights into the genetic mechanisms underlying reproductive adaptability in Tibetan sheep (Ovis aries)

The Tibetan sheep is an ideal model animal for investigating adaptations to hypoxia and an important livestock species; however, the reproductive mechanisms that characterize its adaptive responses in extreme environments remain poorly understood. In this study, we employ single-nucleus RNA sequencing to characterize the transcriptomic landscape of the Tibetan sheep testis at four key developmental stages: newborn, pre-sexual maturity, and post-sexual maturity to adulthood. We constructed a single-nucleus transcriptomic atlas and identified two distinct subtypes of spermatogonial stem cells (SSCs): quiescent and active. Notably, we observed that pre-sexually mature Sertoli cells exhibit three distinct transcriptional states. Furthermore, we also identified a transitional state Sertoli cell that links immature and mature Sertoli cells. Analysis of testicular intercellular communication networks provides evidence for understanding somatic-germ cell interactions during spermatogenesis. Our study provides a comprehensive atlas of Tibetan sheep testicular development, revealing key insights into the dynamic changes and regulatory mechanisms of spermatogenesis and somatic cell maturation from birth to adulthood. These findings contribute to a detailed understanding of the genetic mechanisms underlying testicular development in Tibetan sheep and offer valuable insights and references for the study and comprehension of reproductive adaptations in other highland male domestic animals.