Figure 2
Hypothyroidism alters supporting pillar cell development. (A) Immunofluorescence for pillar cell marker p75ntr (pink; arrowhead) is unchanged relative to control (left) in hypothyroid conditions (right) at E16 and P0, but persists in pillar cells (PCs) at postnatal day 3 (P3) as shown by inset (box). Tight junction protein Zonula-Occludens 1 (ZO-1) immunolabeling (green) is decreased in hypothyroid conditions at E16 and slightly decreased at P0 and P3. (B) Confocal micrographs of cross-sections immunolabeled for calcium-binding protein S100-A1 (pink) show increased immunofluorescence in PCs under hypothyroid conditions (right) at P3 and postnatal day 6 (P6). (C) Quantification of relative fluorescence intensity (mean ± s.e.m. A.U.) indicates increased phalloidin-labeling in P0 OHCs and PCs and decreased S100-A1 in OHCs and PCs from P0 hypothyroid cochleae. The increased intensity of S100-A1 persists in PCs as late as P6 (**p-value < 0.01, *p-value < 0.05). (D) PC marker CD44 decreases in PCs (box, inset) in hypothyroid cochleae at P6, suggesting that later differentiation of hypothyroid PCs is disrupted. Scale bar, 20 μm, applies to all confocal projections, which are representative of 6–9 samples.