Genetically-defined lineage tracing of Nkx2.2-expressing cells in chick spinal cord

To analyze OL development in the spinal cord, chick embryos are widely used for genetic modification by electroporation or for transplantation experiments, because it is relatively easy to manipulate them compared with mouse embryos. However, genetic modification by electroporation is not appropriate for glial development analyses because glia proliferate vigorously before maturation. In order to overcome these problems, we established a novel method to permanently introduce exogenous gene into a specific cell type. We introduced the CAT1 gene, a murine retroviral receptor, by electroporation followed by injection of murine retrovirus. By using this method, we successfully transduced murine retrovirus into the chick neural tube. We analyzed cell lineage from the p3 domain by restricting CAT1 expression by Nkx2.2-enhancer and found that most of the labeled cells became OLs when the cells were labeled at cE4. Moreover, the labeled OLs were found throughout the white matter in the spinal cord including the most dorsal spinal cord. Thus p3 domain directly generates spinal cord OLs in the chick spinal cord.