Influence of embryo transfer on embryo preimplantation development.

OBJECTIVE: To investigate the impact of injection speeds of the transferred load on embryo development. DESIGN: A laboratory model for in vitro simulation of ET was developed to investigate the impact of varying injection speeds of the transferred load on embryo development. SETTING: Academic research institutes of reproduction biotechnology and private centers of reproductive medicine. ANIMAL(S): Mouse hybrid F(1) females (C57bl/10 J × CBA-H; N = 15) aged 2-3 months. INTERVENTION(S): In vitro exposure of mouse embryos with either the fast ET (ejection speed, >1 m/s) or slow ET (ejection speed, <0.1 m/s) and consecutive culture for 36 hours. MAIN OUTCOME MEASURE(S): Development rate, morphology and apoptotic index of embryos. RESULT(S): The development rate was the slowest in embryos exposed to the fast ET. Morphological changes in response to ET were observed only among embryos exposed to the fast ET. The mean apoptotic index was 17.6% in the group exposed to the fast ET, 5.6% in the group exposed to the slow ET, and 2.58% in the control group. CONCLUSION(S): A reduction of the ejection speed of the transferred load allows avoidance of a developmental delay and diminishes injury of the embryos. Therefore, it is reasonable to suggest transferring the embryos at the lowest possible ejection speed.

Pressure induced nucleus DNA fragmentation.

PURPOSE: The present study was designed to investigate the impact of pressure on nuclear DNA integrity in viable cells of mouse blastocysts. METHODS: The blastocysts of hybrid F1 females [(C57Bl/10 J × CBA-H);N = 15] aged 2-3 months were exposed into the pressure impulse lasting ~0.021 s and characterized by a positive pressure peak of ~76 mmHg. The nuclear DNA fragmentation index of mouse blastocysts was assessed by TUNEL assay within 60 s after exposure to pressure impulse. RESULTS: The mean nuclear DNA fragmentation index was significantly higher in the experimental group (83%) than in the control group (19.7%); p < 0.001. CONCLUSION(S): A low magnitude pressure impulse can induce nuclear DNA fragmentation in mouse blastocysts. The compression and decompression forces appearing during pressure fluctuations are responsible for the observed DNA shearing.

Influence of embryo transfer on blastocyst viability.

OBJECTIVE: To investigate the impact of injection speeds of the transferred load on embryo viability. DESIGN: Laboratory model for in vitro simulation of embryo transfer (ET). SETTING: Academic research institutes of reproduction biotechnology and private centers of reproductive medicine. ANIMAL(S): Mouse hybrid F1 females, C57bl/10J × CBA-H (N = 15), aged 2 to 3 months. INTERVENTION(S): In vitro exposure of mouse blastocysts to either fast ET with an ejection speed of the transferred load of >1 m/s or slow ET with an ejection speed of <0.1 m/s. MAIN OUTCOME MEASURE(S): Morphologic changes and apoptotic index of blastocysts. RESULT(S): Morphologic changes in response to ET were most prevalent in blastocysts exposed to fast ET. The mean apoptotic index was 52% in the group exposed to fast ET, 25% in the group exposed to slow ET, and 12.8% in control group. CONCLUSION(S): Fast ejection of the transferred load can trigger both morphologic changes and apoptosis in mouse blastocysts. A reduction of the ejection speed of the transferred load minimizes injury to the embryos. Therefore, embryos should be transferred at the lowest possible speed.