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.