(a)
(b)
(c)
(d)
(e)
(f)
Figure 1: Schematic representation of the open (aperta) and close (occulta) types of spina bifida. (a) Myeloschisis which represents the most severe form of open spina bifida. (b) Myelomeningocele which represents another typical severe form of open spina bifida (spina bifida aperta/spina bifida cystica). The typical representation is that of the spinal cord lying outside the spinal canal. (c) Meningocele that represents open or close spina bifida (the skin may or may not be present) but spinal cord does not lie outside the spinal canal. (d) Lipomyelomeningocele that represents closed spina bifida (spina bifida occulta) (covered with skin) but spinal cord is intermeshed with lipid globules (in yellow). (e) Lipomeningocele that exhibits closed spina bifida but spinal cord does not lie outside spinal canal even though lipid globules are present. (f) Spinal dorsal dermal sinus tract; spina bifida occulta with vertebral arches missing (often asymptomatic and is thought to be a mesodermal defect and a defect of secondary neurulation).