中文摘要：

本文采用RT-PCR和荧光定量PCR对牦牛SYCP3基因的组织表达，以及SYCP3基因在牦牛和犏牛睾丸组织中的表达水平进行分析。结果表明，SYCP3基因在牦牛睾丸组织中特异表达，牦牛与犏牛睾丸组织中SYCP3基因的表达水平差异极显著（P〈0．01）。睾丸和附睾组织切片显示，牦牛睾丸组织中可见各级生精细胞，附睾内可见发育良好的精子，而犏牛睾丸组织中无次级精母细胞和更高级生精细胞、附睾内未观测到精子，与人和小鼠SY-CP3基因缺失或表达水平降低出现的表型一致，可以认为SYCP3基因的表达水平可能与犏牛的雄性不育有一定的关系。

英文摘要：

The expression level of SYCP3 in yak and cattle-yak was studied by RT-PCR and real- time quantitative PCR in this paper. The results showed that SYCP3 was specifc expressed in yak testis, and the difference of expression level between yak and cattle-yak was extremely remarka- ble （P~0. 01）. The tissue sections of testis and epididymis showed that there wasn＇t secondary spermatocytes or spermatids in cattle-yak testis, and sperm could＇t be observed in the epididy- mis. However, there were all levels of spermatogenic cells in yak testis, and sperms grew well in epididymis which was the same represent as man and mice lack or low express with SYCP3. SY- CP3 gene was likely to have a relationship with male infertility of cattle-yak.