Convergent extension leads to narrowing and lengthening of the neuroepithelium, a process that has been suggested also to assist neural fold elevation via axial elongation [105, 226–228]. However, the lengthening of the body axis is disrupted by manipulation of gene function required for convergent extension; whilst the neural folds are still able to elevate, convergent extension still fails [227, 229, 230]. Hence, convergent extension and neural fold elevation are separable processes. Elevation of the neural folds at high levels of the spinal neuraxis results from the formation of a median hinge point (MHP) (Figure 3(b)) in a process termed Mode 1 neurulation [215, 231, 232]. The neural folds remain straight along both apical and basal surfaces, resulting in a neural tube with a slit-shaped lumen. Mode 1 neurulation occurs during formation of the spinal neural tube in 6–10-somite stage embryos, as shown in Figures 4(a) and 4(b).