Two-photon fluorescence real-time imaging on the development of early mouse embryo by stages

Mouse zygotes are widely used in developmental biology and transgenic animal research. Two-photon laser scanning microscopy is particularly useful in four-dimensional observation of big and thick biological samples, such as mouse embryo. The early mouse embryo development from zygote to 8-cell stage compaction was observed in real-time by stages using two-photon laser scanning microscopy in this paper. During our experiment, several scanning parameters were optimized in different development stages. The initial cleavages of mouse embryo, from the zygote to 2-cell, 2-cell to 4-cell, 4-cell to 8-cell, and the compaction at 8-cell stage were observed. During the first stage, localized intracellular calcium elevation along with the cleavage furrow and the asymmetric zygote cytokinesis was detected. The relation between the asymmetry and the location of the second polar body was investigated. The rotational cleavage of mouse embryo was also observed in the experiment. These results would be helpful to further research on mammalian embryonic development.