Symmetry breaking in the early mammalian embryo: the case for quantitative single-cell imaging analysis.

In recent years, advances in imaging probes, cutting-edge microscopy techniques and powerful bioinformatics image analysis have markedly expanded the imaging toolbox available to developmental biologists. Apart from traditional qualitative studies, embryonic development can now be investigated in vivo with improved spatiotemporal resolution, with more detailed quantitative analyses down to the single-cell level of the developing embryo. Such imaging tools can provide many benefits to investigate the emergence of the asymmetry in the early mammalian embryo. Quantitative single-cell imaging has provided a deeper knowledge of the dynamic processes of how and why apparently indistinguishable cells adopt separate fates that ensure proper lineage allocation and segregation. To advance our understanding of the mechanisms governing such cell fate decisions, we will need to address current limitations of fluorescent probes, while at the same time take on challenges in image processing and analysis. New discoveries and developments in quantitative, single-cell imaging analysis will ultimately enable a truly comprehensive, multi-dimensional and multi-scale investigation of the dynamic morphogenetic processes that work in concert to shape the embryo.