Hierarchical interactions that regulate craniofacial development and evolution Rich Schneider Department of Orthopaedic Surgery, University of California at San Francisco Craniofacial development is a highly dynamic and hierarchical process that involves multiple gene regulatory networks, distinct embryonic lineages, and reciprocal signaling interactions among cells and tissues. Mechanisms that orchestrate the various aspects of this complex process and ultimately enable the neural, skeletal, muscular, vascular, and epidermal components of the head to become structurally and functionally integrated, remain unclear. Our research focuses on the extent to which one progenitor population, the neural crest, serves as a primary source of patterning information during craniofacial development. Cranial neural crest cells originate along the dorsal margins of the neural tube, and they migrate extensively throughout the head. Their derivatives include dermis, cartilage, bone, and muscular connective tissues, and they interact extensively with non-neural crest-derived elements such as blood vessels, muscles, epidermis, and nerves. To test the regulatory abilities of the neural crest, we have established an experimental chimeric system using two distinct avian species, quail and duck. This approach exploits the fact that embryonic quail and duck are morphologically distinct and have considerably different rates of maturation. We transplant pre-migratory neural crest cells between quail and duck embryos, which challenges resultant chimeras to assimilate donor versus host-specific differences in growth and morphology. We find that within quail-duck chimeras, donor neural crest cells execute autonomous molecular programs and regulate gene expression in adjacent host tissues. This in turn, establishes the timing of histogenesis, and affects the size, shape, and location of anatomical structures derived from both the donor and the host. Thus, neural crest cells function as a primary source of spatiotemporal patterning information during craniofacial development, and in this capacity have played an essential role in facilitating morphological change during the course of evolution.

Hierarchical interactions that regulate craniofacial development and evolution

Rich Schneider

Department of Orthopaedic Surgery, University of California at San Francisco

Craniofacial development is a highly dynamic and hierarchical process that involves multiple gene regulatory networks, distinct embryonic lineages, and reciprocal signaling interactions among cells and tissues. Mechanisms that orchestrate the various aspects of this complex process and ultimately enable the neural, skeletal, muscular, vascular, and epidermal components of the head to become structurally and functionally integrated, remain unclear. Our research focuses on the extent to which one progenitor population, the neural crest, serves as a primary source of patterning information during craniofacial development. Cranial neural crest cells originate along the dorsal margins of the neural tube, and they migrate extensively throughout the head. Their derivatives include dermis, cartilage, bone, and muscular connective tissues, and they interact extensively with non-neural crest-derived elements such as blood vessels, muscles, epidermis, and nerves. To test the regulatory abilities of the neural crest, we have established an experimental chimeric system using two distinct avian species, quail and duck. This approach exploits the fact that embryonic quail and duck are morphologically distinct and have considerably different rates of maturation. We transplant pre-migratory neural crest cells between quail and duck embryos, which challenges resultant chimeras to assimilate donor versus host-specific differences in growth and morphology. We find that within quail-duck chimeras, donor neural crest cells execute autonomous molecular programs and regulate gene expression in adjacent host tissues. This in turn, establishes the timing of histogenesis, and affects the size, shape, and location of anatomical structures derived from both the donor and the host. Thus, neural crest cells function as a primary source of spatiotemporal patterning information during craniofacial development, and in this capacity have played an essential role in facilitating morphological change during the course of evolution.