At 30 days intra uterine life: (A) Heart starts beating, (B) Cerebellum develops, (C) Optical vesicle appears, (D) Pinna appears
Answer is D. (D) Pinna appears # Development of External Ear:> Auricle, or pinna, is formed from about six mesodermal thickenings (called tubercles or hillocks) that appear on the Mandibular (First) & Hyoid (Second) arches, around the opening of the dorsal part of the first ectodermal cleft (i.e. around the opening of the external acoustic meatus).> External acoustic meatus is derived from the dorsal part of the first ectodermal cleft.> Mandibular arch forms only tragus & a small area around it, rest of the auricle being formed from the Hyoid arch.