Isolation and characterization of spermatogenic cells from cattle, yak and cattleyak.

Cattleyak forms the first generation in the cross-breeding of cattle (Bos taurus) and yak (Bos grunniens), the purpose of which is to increase the yak's performance in meat and milk production. The female cattleyak is fertile while the male remains sterile due to spermatogenic arrest. The spermatogenic cells (including spermatogonia and spermatocytes) of cattle, yak and cattleyak have not been successfully isolated so far. In this work, spermatogenic cells were isolated from these bovid species with the STA-PUT method that has been previously used for germ cell sorting in human and mouse, and the isolated cells could be used to investigate the mechanisms involved in male sterility observed in cattleyak. The characteristics and size of the isolated cells were investigated through microscopic examination, and the cell types were identified by RT-PCR amplification of the marker genes. The purity of spermatogonia and spermatocytes isolated from each bovid species was found to be higher than 85%. The spermatogonium diameter of cattle (10.10 ± 1.04 μm) and yak (14.90 ± 2.30 μm) were significantly larger (P < 0.01) than that of cattleyak (8.60 ± 0.92 μm). The spermatocyte diameter of cattle (19.40 ± 1.50 μm) and yak (20.50 ± 2.42 μm) were also significantly larger (P < 0.01) than that of cattleyak (17.70 ± 2.05 μm). Therefore, the STA-PUT was again validated to be a convenient, economical and efficient method for isolation of spermatogenic cells as it yields more cells within a short time frame.