Figure 5. Ectopic Emx2 reverses hair bundle polarity in the saccule and cristae but not organ of Corti.
(A–D) Saccule, (E–J) anterior and lateral cristae (AC and LC), as well as (K–N) organ of Corti of RosaEmx2/+ (A–B, E–G, K–L) and Gfi1Cre/+;RosaEmx2/+ (C–D, H–J, M–N) inner ears at E18.5 (n = 7). In the Gfi1Cre/+;RosaEmx2/+ saccule, bundle polarity in the OR (outer region) is reversed by approximately 180° (C–D) compared to controls (A–B). (E–J) In control cristae, hair bundles point toward the anterior direction in the AC (F) and medial direction in the LC (G), whereas these polarities are reversed in AC (I) and LC (J) of Gfi1Cre/+;RosaEmx2/+ ears, pointing toward posterior and lateral directions, respectively (H–J). (K–N) No difference in hair bundle polarity is apparent between control (K–L) and Gfi1Cre/+;RosaEmx2/+ (M–N) organ of Corti. IHC, inner HCs (asterisk); OHC, outer HCs (bracket). (O) Schematic diagrams illustrating hair bundle polarity pattern in control and Emx2 GOF sensory organs of the inner ear.