Abstract
Vol.38 No.2
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Original
Morphokinetic analysis of development to the morula of mouse embryos fertilized in vitro using an incubator with time-lapse cinematography
JMOR, 38(2) 61-68, 2021
The preimplantation development of mouse oocytes fertilized in vitro was assessed in an incubator with time-lapse cinematography to evaluate morphokinetic development with higher precision. Fast-developing embryos completed compaction at 58 h after insemination and developed to morulae, but 39% of the cultured embryos had not completed compaction at 72 h after insemination. In contrast, at 24, 48, and 96 h after insemination, most cultured embryos were observed to have developed to the 2-cell, 4-cell, and blastocyst stages, respectively. Mouse embryos cultured in vitro reached the 2-cell stage at 18 h, the 4-cell stage at 41 h, initiated compaction at 59 h, and formed morulae at 70 h, and blastocysts at 87 h after insemination on average. Interestingly, compacting embryos during development to the morula showed a loosening of compaction due to an increase in the number of blastomeres accompanying cell division. Compaction partially regressed with cell division in compacting embryos, making judgement of the completion of compaction dependent on the timing of observation. Observations at conventional 24-h intervals misjudged the development to the morula. Determination of mouse embryonic development 72 h after insemination may be assessing compacting and compacted morula rather than compacted morula.
