Cell to cell adhesion provides impetus for positional cell migration . This may suggest that PCP driven events in the surface ectoderm may play a role in neural tube closure, as suggested in the chick embryo . Epidermal constriction has also been shown to be crucial for spinal neural tube closure in the frog, while the surface ectoderm was shown to be necessary for spinal neural tube closure in the mouse [287, 311].