Effects of opening the incubator on morphokinetics in mouse embryos

Purpose:

The aim of this study was to evaluate the effects of incubator door openings by the sensitive measurement of morphokinetics using time-lapse imaging.

Methods:

To mimic lab practice and to evaluate minimal changes in culture conditions a randomized parallel group study with mouse embryos was designed. 249 murine zygotes derived from 31 mice were randomly distributed into two groups. Embryos of the control group were non-invasively monitored with a Primovision time-lapse system (Vitrolife) in the incubator that was completely closed for 5 days, while the conditions for the embryos in the treatment group were interrupted by two door openings per day of 10 seconds each.

Results:

Door opening twice per day did not lead to significant differences in blastocyst formation rate (p = 0.820), however significantly more embryos hatched in a shorter duration (p = 0.011), and the embryos transitioned more quickly from 2C to 3C, from 3C to 4C, from 2C to 5C and from 5C to blastocyst stage (p < 0.001 in cc2, p = 0.037 in cc3, p = 0.002 in t2 to t5, and p = 0.015 in t5 to blastocyst). Size of the blastocysts from the treatment group was 1.562 µm smaller compared to that of control embryos (p = 0.016).

Conclusions:

Even disruptions in culture conditions as simple as incubator door openings lead to measurable, significant changes in morphokinetics that would have been missed with standard parameters such as blastocyst rate. This underlines the relevance of undisturbed and stable culture conditions and emphasizes the need for further research in this field.