Time-lapse imaging of cleavage divisions in embryo quality assessment

Abstract

fertilization (IVF) is one of the most important procedures for treating infertility. As several embryos are usually produced in a single IVF cycle, it is crucial to select only the most viable ones for transfer to the patient. Morphokinetics, i.e. analysis of the dynamics of cleavage divisions and processes such as compaction and cavitation, has provided both biologists and clinicians with a new set of data regarding embryonic behaviour during preimplantation development and its association with embryo quality. In the current review, we focus on biological significance of morphokinetic parameters and show how they can be used to predict a reproductive outcome. We also explain the statistics behind the predictive algorithms and discuss the future perspectives of morphokinetics.

Time-lapse technology for embryo culture and selection

“…The so-called morphokinetic variables are the morphologic and cleavage features documented at exact time points during the embryo development, such as pronuclear appearance and disappearance, cell divisions, and blastocyst formation (see more in guideline by Ciray et al) (41). Large datasets including timing of certain development events have been analysed to create algorithms to predict implantation and live birth (42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52). Embryos have been classified using individual time-lapse morphokinetic characteristics and related to outcome measured as implantation or live birth.…”

Time-Lapse Microscopy

“…TLM is emerging as a promising clinical technique for selecting embryos for transplantation, although the discussion is still under way whether TLM may become an alternative to preimplantation genetic screening [271,272]. The so-called morphokinetic analysis [273] by TLM is aimed to assess the number, development and quality (viability) of embryos by monitoring cleavage anomalies, multinucleation [274] or specific cell cycle kinetics [274,275] and cleavage divisions [276], aneuploidy [277,278], which is considered as a key causal factor of delays in embryonic development toward a blastocyte [278], and even chromosomal abnormalities [279]. Although more clinical research is required to finally prove that TLM can identify the best embryo for transfer and has an advantage over the conventional incubation of embryos [280], TLM is under consideration for patenting as a method for selecting embryos for implantation [281,282].…”

Impact of sperm characteristics on time‐lapse embryo morphokinetic parameters and clinical outcome of conventional in vitro fertilization

“…The introduction of time‐lapse imaging technology allows continuous observation of embryo development without removal from controlled and stable incubator condition. This technology offers several potential advantages over conventional methods, including improved culture conditions with decreased frequency of handling and exposure of embryos to the risks of stress from temperature changes, high oxygen exposures, and pH changes in the culture media 1,2 . Also, by serial imaging, more information on embryo development is obtained, allowing morphokinetic monitoring (ie, assessment of the quality of embryos by tracking the timing of events and length of different intervals in embryo development), which adds another dimension to embryo selecting and grading 3 .…”