Advancements in Spermatogenesis In Vitro: From Murine Success to Human Applications.

Background: Male infertility due to spermatogenic failure remains a global challenge. While in vitro spermatogenesis (IVS) offers potential for fertility preservation, recapitulating the complex, species-specific testicular niche remains a formidable task. This review evaluates IVS progress and bottlenecks across rodents, primates, domestic animals, and humans. Methods: This review summarizes a comprehensive literature synthesis of IVS methodologies, including organ culture, microfluidics, 3D organoids, and induced pluripotent stem cell (iPSC)-derived systems. Particular focus was placed on the technical evolution from the foundational gas-liquid interface method to the development of bioengineering platforms. Main Findings: Murine IVS systems have successfully and consistently produced fertile offspring. Conversely, human and non-human primate models show meiotic arrest, with differentiation typically stagnating at pre-meiotic stages. Although domestic animal models have occasionally yielded haploid cells, efficiency remains low. Recent single-cell analyses suggest that disrupted somatic-germ cell communication is a key driver of these failures. Conclusion: Bridging the gap between rodent success and human application requires integrating developmental biology with precision engineering. Future efforts must focus on establishing rigorous epigenetic and functional validation to ensure the safety and efficacy of IVS for clinical reproductive medicine.