A new cell surface relationship between neuroepithelial cells during rat neural tube development

Electron microscopic examination of the developing neural tube in 11th to 13th day rat fetuses revealed a new cell surface relationship between differentiating neuroepithelial cells. Cytoplasmic projections possessing terminal dilations were observed extending from neuroepithelial cells through cytoplasmic furrows into large coated pits at the surface of adjacent cells. This cell-to-cell relationship provides a mechanism for the internalization of surface molecules and possibly even cytoplasmic constituents. Communication between donor and recipient cells mediated in this way suggests a route for the sharing of macromolecules, including cytoplasmic fragments, which could function as regulators in embryonic development and differentiation.