Previous work has suggested that efferent fibers, derived from facial branchial motoneurons, follow afferents and for that reason reflect in detail all connectional deviations of afferents [16,30-32]. Our data agree with this scenario but extend it. Specifically, efferent fibers may suffer the same loss of their molecularly unknown neurotrophic support as do afferents and therefore show the same spatio-temporal profile of loss (Fig. 3). Alternatively, efferent fibers can sustain established connections only as long as afferent fibers are present. More information on the actual molecular support of efferent fibers in the ear is needed before those two possibilities can be distinguished.