Esco Miri® TL Time-Lapse With Integrated pH Monitoring

Time-lapse technology allows for the selection of viable embryo(s) based on morphokinetic parameters. Morphokinetic parameters include pronuclei (PN) formation or the assessment of pronuclei, cell cleavage patterns/rates, embryo symmetry, fragmentation progression and reabsorption, multinucleation, and cell compaction rate/timing.

Over the last few decades, embryologists have used static observation on key development days to select the best embryos for transfer, cryopreservation, or genetic screening.  Time-lapse photography advances embryo culture methods by recording the timing of otherwise unnoticed development events and intracellular processes during  in vitro culture.

Time-lapse imaging technology provides many culture benefits. Uninterrupted culture conditions add control to temperature and pH values, crucial parameters to stabilize and track for optimal embryo culture. Unique developmental patterns such as Direct Cleavage (DCL), Reverse Cleavage (RCL) and Multinucleation are observable using through continuous monitoring technology.

Some examples of embryo culture patterns time-lapse notes are a direct cleavage from two to three cells, or also known as DC2-3. This type of cleavage has a statistically significantly lower implantation rate than embryos with normal cleavage patterns[1]. Cleavage-stage embryos that were observed to reduce in cell number are said to undergo a process referred to as reverse cleavage or blastomere fusion. In the majority of cases, two blastomeres of an embryo fuse resulting in a hybrid cell containing two nuclei. About 27.4% of embryos undergo Reverse Cleavage during the first three cleavage cycles[2] and multinucleation may occur at different times during the developmental period and can disappear in a very short period [3]. With time-lapse microscopy, it is possible to evaluate optimal time points such as multinucleation between cell division events and cell division time ranges.

Time-lapse gives the lab more information while using non-invasive culture strategies. For example, clinical pregnancy rates have been found to be better for embryos cultured in a time-lapse incubator, which is mainly attributed to the stable culture environment and the use of morphokinetic parameters for embryo selection[4].

Time-lapse has recently increased knowledge of embryo development in the field, including:

• Analyzing the relationship between ovarian stimulation and early embryo morphokinetics [5,6]
• The effects of blastomere removal on embryo development, including delayed compaction and an alteration to the hatching mechanism [7]
• The effects of atmospheric oxygen concentration (20%) on cell kinetics [8]
• Discovery of a novel mechanism for blocking polyspermy through time-lapse fertilization observation [9]