Failure of closure of the anterior (rostral) neuropore during the fourth week of gestation results in which condition?
- A Spina bifida aperta in the lumbosacral region
- B Anencephaly ✓
- C Holoprosencephaly
- D Arnold-Chiari malformation
Correct answer: B. Anencephaly
Explanation
The rostral neuropore closes at about day 25 and the caudal neuropore at about day 27. Failure of rostral neuropore closure prevents formation of the forebrain and calvarial vault, producing anencephaly with an open defect involving the skull and exposed neural tissue. Failure of caudal neuropore closure produces spina bifida defects, while holoprosencephaly is a failure of cleavage of the prosencephalon, not of neuropore closure.
Reference: Langman's Medical Embryology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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