Chromosomal abnormality of embryos is one of the main causes of pregnancy failure. Preimplantation genetic testing (PGT) can significantly improve the implantation rate and the rate of continuous pregnancy by selecting chromosomally normal embryos to transfer, but the invasive nature and operational complexity of PGT limit its clinical application. Therefore, the development of a non-invasive, rapid and economical method for embryo genome detection would represent a progress in assisted reproduction. In recent years, with the discovery of cell-free genomic DNA in spent embryo culture media and the blastocoel fluid, genetic analysis of cell-free DNA has been reported in evaluating the genetic constitution of embryos, however, the published studies lack consistent conclusions. In this review, we have summarized the progress of cell-free genomic DNA in PGT and discussed its current limitations and future clinical implications.

Chromosomal abnormality of embryos is one of the main causes of pregnancy failure. Preimplantation genetic testing (PGT) can significantly improve the implantation rate and the rate of continuous pregnancy by selecting chromosomally normal embryos to transfer, but the invasive nature and operational complexity of PGT limit its clinical application. Therefore, the development of a non-invasive, rapid and economical method for embryo genome detection would represent a progress in assisted reproduction. In recent years, with the discovery of cell-free genomic DNA in spent embryo culture media and the blastocoel fluid, genetic analysis of cell-free DNA has been reported in evaluating the genetic constitution of embryos, however, the published studies lack consistent conclusions. In this review, we have summarized the progress of cell-free genomic DNA in PGT and discussed its current limitations and future clinical implications.

Aim To observe the influences of dexmen-detomidine on the spontaneous contraction of duodenal smooth muscle of rabbits in vitro and explore the mech-anisms.Methods The rabbits ( male or female ) were stunned and the duodenums were isolated .The sam-ples of duodenal segments were connected with tension transducer , which were then put into oxygen saturation Krebs-Henseleit ( K-H) solution .The influences of dex-mendetomidine on amplitude ( AM ) and frequency ( FR ) of duodenal smooth muscle were recorded by BL-420 F biological signal processing system .The cu-mulative dosing method was used to observe the differ-ent concentrations of dexmedetomidine on duodenal smooth muscle spontaneous contraction .Glibenclamide ( Gli) was added to K-H solution before dexmendeto-midine.In the calcium-free K-H solution, calcium chloride and rynodine were added before dexmendeto-midine.The mechanisms of dexmendetomidine were studied .Results ① Dexmendetomidine reduced the amplitude of spontaneous contraction of duodenal smooth muscle in rabbits in a dose-dependent manner ( P<0.05 or P<0.01 ) , while the frequency was not obviously influenced ( P >0.05 ) .② Gli ( P <0.05 ) partly abolished the inhibitory effects of dexmendetomi-dine on duodenal smooth muscle .③ Dexmendetomi-dine inhibited the contraction of duodenum smooth muscle induced by calcium chloride ( P <0.05 ) and rynodine ( P<0.05 ) application into calcium-free K-H solution.Conclusion Dexmendetomidine inhibits the spontaneous contraction of duodenal smooth muscle of rabbits in vitro.The mechanisms may be related to ac-tivating ATP sensitive potassium channels , inhibition of the extracellular calcium influx via cell membrane and intracellular calcium release via sarcoplasmic reticulum in duodenal smooth muscle .