3 research outputs found
New methods for chicken embryo manipulations
The capacity to image a growing embryo while simultaneously studying the developmental function of specific molecules provides invaluable information on embryogenesis. However, until recently, this approach was accomplished with difficulty both because of the advanced technology needed and because an easy method of minimizing damage to the embryo was unavailable. Here, we present a novel way of adapting the well-known EC culture of whole chick embryos to time-lapse imaging and to functional molecular studies using blocking agents. The novelty of our method stems from the ability to apply blocking agents ex ovo as well as in ovo. We were able to study the function of a set of molecules by culturing developing embryos ex ovo in tissue culture media containing these molecules or by injecting them underneath the live embryo in ovo. The in ovo preparation is particularly valuable, because it extends the period of time during which the developmental function of the molecule can be studied and it provides an easy, reproducible method for screening a batch of molecules. These new techniques will prove very helpful in visualizing and understanding the role of specific molecules during embryonic morphogenesis, including blood vessel formation
Early regulative ability of the neuroepithelium to form cardiac neural crest
The cardiac neural crest (arising from the level of hindbrain rhombomeres 6–8) contributes to the septation of
the cardiac outflow tract and the formation of aortic arches. Removal of this population after neural tube
closure results in severe septation defects in the chick, reminiscent of human birth defects. Because neural
crest cells from other axial levels have regenerative capacity, we asked whether the cardiac neural crest might
also regenerate at early stages in a manner that declines with time. Accordingly, we find that ablation of
presumptive cardiac crest at stage 7, as the neural folds elevate, results in reformation of migrating cardiac
neural crest by stage 13. Fate mapping reveals that the new population derives largely from the
neuroepithelium ventral and rostral to the ablation. The stage of ablation dictates the competence of residual
tissue to regulate and regenerate, as this capacity is lost by stage 9, consistent with previous reports. These
findings suggest that there is a temporal window during which the presumptive cardiac neural crest has the
capacity to regulate and regenerate, but this regenerative ability is lost earlier than in other neural crest
populations