FIG. 1.

Grading system used to analyze Phex ^H-D /Y mice after ECochG. Cochleae of P21 mice stained with hematoxylin and eosin, illustrating the range of severity of ELH possible at this stage. The magnification is ×10 for all panels. Here, grades 1–3, but not grade 4, were observed. Grade 4 is rare, but possible at P21; to illustrate this, a sample of grade 4 ELH obtained from other experiments (unpublished observations) is included here. ST scala tympani, SM scala media, SV scala vestibuli, RM Reissners’ membrane.