Mammalian neural tube grafting experiments: an in vitro system for mouse experimental embryology

We have developed a simple experimental technique which consists of explanting the mouse embryo anterior neural tube--the presumptive brain anlage--onto polycarbonate membranes. The neural epithelium of the explants maintained both its original topology and topography for at least two days in culture. Analysis of cell death in the explants by assaying propidium iodide uptake showed high viability of neuroepithelial cells during the culture period. Both the pattern of gene expression and the initial steps of neural cellular differentiation were well preserved, being similar to those which occur in the normal in vivo situation. We show here two applications of this tissue culture technique which is similar to that which has been previously employed for avian embryo models. The first involves neuroepithelial grafting experiments by heterotopic transplantation of the zona limitans intrathalamica (ZLI) into the mesencephalon and the second consists of fibroblast growth factor (FGF8) protein interaction studies using soaked bead insertions. This in vitro system constitutes a powerful experimental embryological tool which can have other applications including time-lapse imaging and electrophysiology.