Fig. 6. Normal vestibular efferent location but abnormal medial and lateral olivocochlear efferent neuron localization in the reeler mutant. (A,B) Retrograde labeling of the OC and VEN from the VIIIth ganglion (bilateral injections). Drawings of labeled cells with clear labeled projections and which are not VII precursor cells, were done to clarify injection interpretation. (A) The OCs were identified in a ventral position in control mice. (B) These cells were located ectopically, in close association with VEN, in reeler mutants (circled). (C,D) Retrograde labeling of the OC and VEN from the otocyst (left side) in reeler mutants, to label LOC and MOC cells. Dorsally located cells were labeled on contralateral and ipsilateral sides, which indicated that MOC are affected in reeler mutants (C). A few ipsilateral cells close to the pial surface were labeled on the ipsilateral side only (arrow, D), which should reflect LOC cells migrating to the pial surface. LOC is the major component of the OC precursors, this observation might reflect subpopulation migratory properties, independent of reelin. fp, floor plate; LOC, lateral olivocochlear efferents; MOC, medial olivocochlear efferents; OC, olivocochlear efferent; VEN, vestibular efferent nucleus.