School of Medicine, Health Sciences Centre, University College Dublin, Dublin, Ireland.
School of Medicine, University of Nottingham, Nottingham, United Kingdom.
Sci Rep. 2020 Apr 10;10(1):6255. doi: 10.1038/s41598-020-63077-6.
In artificial insemination the use of sex-sorted bovine sperm results in reduced conception, the causes of which are only partly understood. Therefore, we set out to investigate the effects of sexing on bovine sperm function and early embryonic development. Computer-assisted semen analysis (CASA) of sperm of the same bulls (n = 5), before and after sexing, demonstrated significantly reduced fast (A) and slow (B) progressively motile sperm (p < 0.05) after sexing. Sexed-sperm also revealed significantly less hyperactivated sperm (p < 0.05). As shown by time-lapse videomicroscopy of in vitro produced embryos (n = 360), embryos derived from sexed-sperm displayed significantly increased incidences of arrest at the 4-cell stage (p < 0.05). The relative risk for shrinkage/fusion of blastomeres with subsequent lysis was 1.71 times higher in the embryos derived from sexed-sperm as compared to conventional embryos (p < 0.05) resulting in significantly reduced blastocyst rates (p < 0.001). The relative risk for cleavage was 2.36 times lower in the embryos derived from sex-sorted sperm (p < 0.001). Additionally, sexed-sperm-derived embryos showed reduced survival times (hazard ratio HR = 1.54, p < 0.001) which were bull dependent (p < 0.001). However, the percentage of apoptotic cells was similar to conventional embryos. Furthermore, embryos derived from sexed-sperm were found to reach developmental stages at similar timings as conventional embryos. Our results suggest that reduced conception rates after sexing are due to altered sperm morphokinetics, decreasing the chance of sperm to reach and fertilise the oocyte, and aberrant early embryonic development.
在人工授精中，使用性别分选的牛精子会导致受孕率降低，但其原因尚不完全清楚。因此，我们着手研究性别分选对牛精子功能和早期胚胎发育的影响。对同一头公牛的精子（n=5）进行计算机辅助精液分析（CASA），发现分选前后快速（A）和慢速（B）前向运动精子的比例明显降低（p<0.05）。分选后的精子中也明显较少出现超激活精子（p<0.05）。通过体外受精胚胎的延时视频显微镜观察（n=360），发现来自分选精子的胚胎明显增加了在 4 细胞阶段停滞的发生率（p<0.05）。与常规胚胎相比，来自分选精子的胚胎中，卵裂球收缩/融合随后裂解的相对风险增加了 1.71 倍（p<0.05），导致囊胚率显著降低（p<0.001）。来自分选精子的胚胎中，卵裂的相对风险降低了 2.36 倍（p<0.001）。此外，分选精子衍生的胚胎显示出存活时间缩短（风险比 HR=1.54，p<0.001），且这种情况依赖于公牛（p<0.001）。然而，凋亡细胞的百分比与常规胚胎相似。此外，来自分选精子的胚胎被发现与常规胚胎达到发育阶段的时间相似。我们的结果表明，分选后受孕率降低是由于精子形态动力学发生改变，降低了精子到达并使卵子受精的机会，并导致早期胚胎发育异常。
