Haoyan Jin

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.

Spermatogonial stem cells (SSCs) have the potential for self‐renewal and differentiation, and normal spermatogenesis maintains a stable number of spermatogonial stem cells and spermatozoa. Spermatogenesis is accompanied by changes in the three‐dimensional structure of chromatin and gene expression, but the structural differences between the stages and the higher‐order chromatin dynamics have not yet been elucidated. Consequently, we conducted a high‐throughput analysis of the chromatin structural organization and gene expression by using porcine spermatogonia (SPG), spermatocytes (SPY) and round spermatids (RS). We found that during spermatogenesis, SPY showed a weaker pattern of chromosomal interactions, attenuated compartmentalisation, and a reduction in the number of TADs (topological associating domains), which was restored during the subsequent period of round spermatids. These findings suggest reprogramming of higher‐order chromatin structures during porcine spermatogonia differentiation. Our results reveal that chromatin structure changes during porcine spermatogenesis, along with changes in gene expression. In conclusion, our study reveals the interrelationships between higher‐order chromatin structure and gene expression in spermatogonia, spermatocytes, and round spermatids, providing new insights into the understanding of spermatogenesis as well as basic theoretical data for male reproductive techniques in biological sciences.