My training is in the field of developmental biology and has been focused primarily on molecular and cellular mechanisms underlying the patterning, differentiation, and evolution of the vertebrate skeleton. Currently in my lab, we have been developing an in vivo avian chimeric transplantation system. The strength of this system lies in the highly divergent growth rates and distinct species-specific morphologies of quail and duck embryos, which we exploit to identify genetic pathways and critical tissue interactions that regulate the spatiotemporal patterning of cartilage and bone. We transplant mesenchymal stem cells from quail to duck embryos. This permits faster developing quail donor-derived mesenchyme and relatively slower maturing duck host tissues to interact with one another continuously from the moment they first meet. Also, chimeras are challenged to integrate species-specific differences in skeletal morphology, particularly in relation to size and shape. By looking for donor-mediated changes during skeletogenesis, we find that within resultant chimeras, quail donor mesenchyme executes autonomous molecular programs and regulates gene expression in adjacent duck host tissues. This in turn, establishes when derivatives of the donor and those of the host undergo differentiation, and determines the size, shape, and location of skeletal structures. Thus, mesenchyme functions as a principal source of spatiotemporal patterning information during skeletal development, and in this capacity has likely played an fundamental role in mediating changes to the skeleton during the course of evolution. A long-term goal of my research is to identify the precise signaling mechanisms through which mesenchymal stem cells exert their affects, which will be essential for devising molecular-based therapies that can induce repair and regeneration of skeletal elements affected by congenital defects, disease, and trauma.