<prompt> Untrue about ectodermal cleft isCervical sinus is found between 2-6 archesVentral pa of the cleft is obliteratedDorsal pa of 1st cleft forms the lining of external earNone of the above  <response>: D. i.e. None of the above1st pharyngeal arch form maxillary prominence producing maxilla zygomatic bones by intramembranous ossificationQ and mandibular prominence producing malleus incus by endochondral ossificationQ. Mandibular division of trigeminal nerve is the nerve of 1st arch- Muscle of facial expression including buccinator develop from 2nd arch so are supplied by facial nerveQ not mandibular nerve. Stapes is the skeletal element of 2ttd arch.Thymus develops from 31 endodermal pouchQ. Ultiinobranchial body forming parafollicular cells of thyroid are derived from 5deg branchial endodermal pouchQ 