In all animal species studied, a zone of altered cell morphology with numerous rounded cell blebs has been observed along the tips of the spinal neural folds, immediately prior to adhesion. The observed surface alterations may reflect a change in the properties of the cells at the adhesion site which correlate with initial adhesion between the folds [234, 236, 301, 302]. Structural observations of the point of adhesion in human embryos have yet to be reported, possibly due to insufficient or poor preservation of material so that surface structures cannot be observed.