Department of Animal Reproduction, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan.
Faculty of Veterinary Science, Prince of Songkla University, Songkhla, Thailand.
Reprod Domest Anim. 2022 Sep;57(9):999-1006. doi: 10.1111/rda.14166. Epub 2022 Jun 6.
The balance between proliferation, differentiation and apoptosis is well-coordinated in spermatogenesis for the timely production of appropriate numbers of sperm in animals. Disruption or decrease in sperm production is due to many conditions, including changes in testicular cell fate balance. Interspecies hybridization of domestic yaks and cattle results in sterility in males because of spermatogenic arrest; however, the underlying mechanisms involved in sterility are still unclear. In the present study, we investigated the proliferation and apoptosis status during the development of yaks and crossbred cattle-yaks using immunohistochemistry of proliferating cell nuclear antigen and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling assays. Testicular tissues from yaks (immature: 1 year old, mature: 2-3 years old) and backcrossed hybrids (2 year old) were collected and used to investigate the expression of each parameter in testicular cells. During the maturation of yak testes, proliferation and apoptosis became active only in spermatogenic cells, and not in other somatic cells, such as Sertoli cells, myoid cells and Leydig cells. Furthermore, hybrid cattle-yak testes maintained proliferation ability but less apoptotic ability in spermatogenic cells when compared to yaks of the same age, suggesting that normal spermatogenic cell fate control is disrupted by changes in the balance between proliferation and apoptosis. In addition, Leydig cell proliferation rate was higher than apoptosis rate in the cattle-yak testes, indicating an increased number of Leydig cells, which may affect spermatogenesis through changes in steroidogenesis. Although epigenetic changes may be involved in cattle-yak testes, further studies are needed to clarify the modulation of proliferation and apoptosis to elucidate the mechanisms of infertility in hybrid cattle-yak males.
在动物的精子发生过程中，增殖、分化和凋亡之间的平衡得到了很好的协调，以便适时产生适当数量的精子。精子生成的破坏或减少是由于许多条件引起的，包括睾丸细胞命运平衡的变化。由于精子发生停滞，家牦牛和牛的种间杂交导致雄性不育；然而，导致不育的潜在机制尚不清楚。在本研究中，我们使用增殖细胞核抗原的免疫组织化学和末端脱氧核苷酸转移酶介导的 dUTP 缺口末端标记法研究了牦牛和杂交牦牛的发育过程中的增殖和凋亡状态。收集了牦牛（未成熟：1 岁，成熟：2-3 岁）和回交杂种（2 岁）的睾丸组织，用于研究睾丸细胞中每个参数的表达。在牦牛睾丸的成熟过程中，增殖和凋亡仅在精原细胞中活跃，而不在其他体细胞（如支持细胞、肌样细胞和间质细胞）中活跃。此外，与同龄牦牛相比，杂交牦牛睾丸中的精原细胞保持增殖能力，但凋亡能力降低，这表明增殖和凋亡之间平衡的改变破坏了正常的精原细胞命运控制。此外，牛牦牛睾丸中的间质细胞增殖率高于凋亡率，表明间质细胞数量增加，这可能通过改变类固醇生成来影响精子发生。尽管表观遗传变化可能参与了牛牦牛睾丸，但需要进一步研究来阐明增殖和凋亡的调节，以阐明杂交牛牦牛雄性不育的机制。
