Dynamic in vivo imaging of mammalian hematovascular development using whole embryo culture.

The yolk sac is the initial site of hematopoiesis in the mammalian embryo. As the embryo develops, blood vessels form around primitive erythroblasts to connect the yolk sac to the embryo, delivering newly formed blood cells to the embryonic circulation. The limited accessibility of the mammalian embryo has made it difficult to study the dynamic changes in cellular development during the formation of the early hematovascular system. Therefore, we have developed a culture system for studying early hematopoiesis, vasculogenesis. and angiogenesis in the mouse embryo. Early embryos (E7.5-E9.5) can be grown on the microscope stage to study the dynamics as vessels form and circulation begins. In addition, this mouse embryo culture system provides an excellent model for understanding the interplay between flow dynamics and cellular development.