Malclosure of the rostral neuropore during the fourth week of | Anatomy embryology histology videos & books

Malclosure of the rostral neuropore during the fourth week of development results in anencephaly and is lethal in the affected newborn. The condition is better termed meroanencephaly because of the presence of the rudimentary brainstem with some functioning nervous tissues. Defects in the closure of the caudal neuropore (choice A) result in varying conditions of spina bifida at the lower end of the spinal cord. The first branchial arch (choice C) and the somites (choice D) do not play any role in the formation of the brain. Fusion of the metopon or forehead (choice E) occurs after birth and also does not play a role in brain formation.