Fig. 8. Formation of normal notochords in embryos lacking the posterior neural plate (notoplate). (A) Control embryos; the axial neural tube can be seen in cross section as a set of four cells lying above the notochord and just below the dorsal epidermis. (B) Embryo lacking posterior neural plate. The axial neural tube is gone and instead a pair of epidermal cells contact the fully formed notochord along the dorsal midline.