Live confocal microscopy of the developing mouse embryonic yolk sac vasculature.

Understanding of mouse embryonic development is an invaluable resource for our interpretation of human embryology. Traditional imaging approaches such as immunofluorescence and in situ hybridization are excellent methods for characterizing gene expression and morphology but lack the ability to reveal the dynamic morphogenesis. Furthermore, mammalian embryonic development occurs in utero, which bars our ability to visualize development in dynamics. With the use of live confocal microscopy, vital fluorescent reporters, and embryo culture methods, we can observe cell migration, proliferation, differentiation, and cell-cell interaction in live developing wild-type and mutant embryos. In this chapter, we will discuss how confocal microscopy can be used to visualize the developing vasculature and hemodynamics of the mouse embryonic yolk sac. We will describe fluorescent protein reporter mouse models allowing to image yolk sac vessel development and blood flow, live embryo culture approaches, and confocal time-lapse imaging methods to study vascular morphology and hemodynamics in early embryos.