In mouse and humans, spina bifida occulta has largely been described as a result of failure of secondary neurulation [3, 215]. However, much has been described of the severity of lipomyelomeningocele [131, 248] in comparison to the somewhat neurologically unperturbed tethered cord phenomenon which is brought on by trapped nerves due to missing vertebral arches . What is evident is that, irrespective of whether or not there is skin covering the neural tube defect lesion, the severity of the condition depends on the level where the site of the lesion is located. Secondary neurulation in the mouse is described as occurring at sacral level 2 . Therefore, to describe lipomyelomeningocele as resulting from failure of secondary neurulation would be artificial.