Live imaging of mouse embryos.

The development of the mouse embryo is a dynamic process that requires the spatial and temporal coordination of multiple cell types as they migrate, proliferate, undergo apoptosis, and differentiate to form complex structures. However, the confined nature of embryos as they develop in utero limits our ability to observe these morphogenetic events in vivo. Previous work has used fixed samples and histological methods such as immunofluorescence or in situ hybridization to address expression or localization of a gene of interest within a developmental time line. However, such methods do not allow us to follow the complex, dynamic movements of individual cells as the embryo develops. Genetic manipulation methods now allow us to label virtually any cell type or protein of interest fluorescently, providing powerful insights into morphogenetic events at cellular and subcellular resolutions. The development of ex vivo embryo culture methods combined with high-resolution imaging now provides a strong platform for observing morphogenetic events as they occur within the developing embryo. In this article, we discuss the advantages of live embryo imaging for observing dynamic morphogenetic events in vivo.