Morphologically, the mouse neural tube undergoes distinct structural changes prior to its closure [7, 215, 221–224]. A summary of the spatiotemporal expression of genes in the mouse neural tube during neurulation is as shown in Table 5. The neuroepithelium narrows and lengthens, a process referred to as convergent extension (Figure 3(a)), in which the polarized cells which form the neuroepithelial plate converge towards the midline, elongate anteroposteriorly, and then intercalate [215, 225].