The process of neurulation in mammals and some other vertebrates is considered discontinuous because it occurs simultaneously at multiple sites along the neuraxis [215–219]. There are three points of de novo neural tube fusion in the mouse, which is the most studied mammalian model (; see Figure 2(a)). Closure 1 occurs adjacent to somite 3 in embryos with 6-7 somites and progresses rostrally and caudally, closure 2 occurs at the midbrain-forebrain boundary at around the 10-somite stage and progresses caudally, and closure 3 occurs at the rostral end of the forebrain, soon after closure 2.