ear pit preauricular p. lens pit a pitlike depression in the ectoderm of the lens placode where the primordial lens is developing. olfactory pit the primordium of a nasal cavity. otic pit a depression appearing in each otic placode, marking the beginning of embryonic development of the internal ear. preauricular pit a small depression anterior to the helix of the ear, sometimes leading to a fistula or congenital preauricular cyst.