Control of Cytodifferentiation in the Cranial Musculoskeletal System

Introduction: Precise temporal control of cell differentiation is essential for craniofacial development. Disruptions to this process result in a range of human birth defects. For example, premature cell differentiation within the osteogenic front of cranial sutures causes craniosynostoses. Conversely, a delay in differentiation of median edge epithelium leads to clefting of the secondary palate. Thus, the timing of differentiation among populations of embryonic cells is a prerequisite for normal facial growth. Mechanisms regulating the differentiation of cranial neural crest into cartilage and bone, and mesoderm into muscle, are not known. We hypothesize that neural crest cells regulate their own temporal differentiation as well as that of adjacent mesoderm. To test this hypothesis, we performed neural crest transplants between two distinct avian species, quail and duck. Our approach exploits the fact that these birds have considerably different rates of maturation, which provides a novel method for identifying time-dependant interactions between populations of neural crest and mesoderm.