Time-lapse observations to analyze the effects of assisted hatching

Assisted hatching (AH) is an artificial disruption of the zona pellucida with the aim of facilitating embryo implantation. We used time-lapse observations of mouse embryos to examine the effect of AH in mouse blastocysts.

AH techniques were performed with acid Tyrode's solution. We compared the rates of blastocyst formation and blastocyst attachment to Ishikawa cells between the control (n = 28) and the AH group (n = 24). To analyze the effects of AH, 8-cell mice embryos were cultured under time-lapse observations (every 15 min). The time required for hatching, the hatching rates, the frequency of contraction, and the contraction rates in the blastocysts were analyzed.

There were no significant differences between the two groups in hatching rate or attachment rate. The times required for hatching were 286 ± 22 min in the AH group and 990 ± 437 min in the control group (P = 0.018). The contraction frequencies in blastocysts were 3.5 ± 0.7 times in the AH group and 7.5 ± 2.5 times in the control group (P = 0.020).

From the time-lapse observations we found that the time required for hatching and the frequency of contraction in blastocysts were both reduced by AH, although blastocyst formation and attachment were not affected.