auditory pits

o·tic pits

paired depression, one on either side of the head of the embryo, marking the location of the future otic vesicles.
Synonym(s): auditory pits

au·di·to·ry pits

(aw'di-tōr-ē pits)
Paired depressions, one on either side of the head of the embryo, marking the location of the otic placodes, the future auditory vesicles.