External auditory meatus is derived from which cleft?: (A) 1, (B) 2, (C) 3, (D) 4
Answer is A. Cleft 1 forms external auditory meatus- surface ectoderm If the pharyngeal clefts are not obliterated by the 2nd pharyngeal arch, they can persist into adulthood as branchial (pharyngeal) cysts.