Development of Simple live-imaging method for viewing the first cleavage of mammalian embryos by using fluorescent chemical probes for DNA and cytoskeletons

Abstract

Abstract Dynamic morphological changes in the chromosomes and cytoskeleton occur in mammals including humans, during early embryonic development, and abnormalities such as embryonic chromosomal aneuploidy occur when development does not proceed normally. In previous reports, the behavior of DNA and cytoskeleton in early mammalian embryos has conventionally been visualized and observed by injecting target molecule mRNA, with a fluorescent substance-expressing gene incorporated, into embryos. However, injecting genetic information into a human embryo to induce the production of unnatural proteins must be carefully considered from an ethical perspective. Therefore, we aimed to develop a simple observation method as a way of gaining knowledge about the first division that can avoid such problems. We visualized the chronological behavior of male and female chromosome condensation in mammalian embryos, beginning in the 2PN zygote, through the first division into the two-cell stage by using fluorescent chemical probes for DNA, microtubules, and microfilaments. This method is simple and does not require genetic manipulation, and its application can be observed at any stage during embryonic development, thereby providing novel insights into embryonic development in many mammals. In particular, it is expected to provide a great deal of cell biological information on the first cleavage of human embryos, which have been reported to exhibit a variety of patterns.