Number of efferent synaptic terminals and synaptic ribbons in macular hair cells.

Values are means ± SEMs. For each group, the number of hair cells tested is given in parentheses. Calretinin-positive hair cells (CR+) and calretinin-negative hair cells (CR–) were statistically analyzed using a two-tailed Student's t-test with unequal variance. All pairwise comparisons were significant at p<10−12 except for the two indicated with asterisks, which were not significant at p<0.5. Efferent synaptic terminals were identified as synapsin-positive structures surrounding the basolateral regions of hair cells. Synaptic ribbons were determined by the presence of distinct CtBP2-positive signals surrounding hair-cell nuclei. Z-stack confocal images with 0.3-µm increments were analyzed in a total of 576 hair cells from six different sacculi.