Background: Mammalian spermatogenesis is critical for the transmission of male genetic information, and single-cell sequencing technology can reveal its complex process. However, at present, there is no research on the dynamic transcription of bovine germ cell population. Results: In this study, we used Stereo-seq to construct a spatial transcription map of bovine testicular tissue at two ages. Four germ cell groups and five somatic cell groups were determined, and functional enrichment characterized their different biological functions and the differences between calves and adult bulls. At the same time, we also defined the subpopulations of cells and marker genes, then, clarified the communications between germ cells. Conclusion: Our study constructed a spatial transcription map of bovine testicular tissue for the first time, and systematically described the dynamic transcription changes during spermatogenesis. These data laid the foundation for the study of spermatogenesis in large mammals and elucidated the transcriptional dynamics underlying male germ cell development.

In livestock farming, the reproductive function and breeding performance of Tan sheep are crucial for enhancing farming efficiency. Despite advances in research on sheep germ cells, studies on the identification of markers for spermatogonia, spermatocytes, and spermatozoa in Tan sheep remain limited and inadequate. In this study, Tan sheep were used as research subjects to investigate the morphological characteristics of testicular tissues, the developmental status of germ cells, and potential novel markers for spermatogonia, spermatocytes, and spermatozoa across different ages (0 days, 60 days, 180 days, and 365 days). Homology of the SMC3, G3BP1, and AKAP4 genes was analyzed via NCBI alignment. The localization and expression characteristics of these genes in the testis tissues of Tan sheep were investigated using HE staining, qPCR, and immunofluorescence double staining. The results showed that from 0 to 365 days of age, with increasing age, spermatogonia, spermatocytes, and spermatids exhibited an orderly distribution, and mature spermatozoa appeared in the tubular lumen, marking the initial establishment of the spermatogenic process. The homology of SMC3, G3BP1, and AKAP4 was 90%, 85%, and 81%. The mRNA levels of SMC3 and G3BP1 in the testes of 60-day-old Tan sheep were significantly increased, while AKAP4 expression showed a gradual increase with advancing age. SMC3 was co-localized with PLZF in undifferentiated spermatogonia, G3BP1 was co-expressed with SYCP2 in spermatocytes, and AKAP4 was co-expressed with PNA in spermatozoa. The findings of this study provide further supportive evidence for novel markers of spermatogonia, spermatocytes, and spermatozoa in Tan sheep.