General cochlear morphology. (A–F) Hematoxylin-eosin staining of midmodiolar paraffin sections of the cochlea at postnatal wk 5 (A, B) and 11 (D–F) in Irs2+/+Ptpn1+/+, Irs2−/−Ptpn1+/+ and Irs2−/−Ptpn1−/− mice. The general cochlear histology of both Irs2−/−Ptpn1+/+ and Irs2−/−Ptpn1−/− mutants (B, E, F) was similar to that in the wild-type mice (A, D), with no obvious alterations, at either age studied. (C) Drawing scheme of the cochlear duct of the basal turn (highlighted in B) and detail of the stria vascularis (StV, small rectangle), which is formed by the basal (B), the intermediate (I) and the marginal (M) cell layers and contains a dense capillary network. (G–I) Hematoxylin-eosin staining of the cochlear duct of the basal turn in Irs2+/+Ptpn1+/+ (G), Irs2−/−Ptpn1+/+ (H) and Irs2−/−Ptpn1−/− mice (I) at postnatal wk 11. Both mutants showed a developed organ of Corti (OC), cochlear ganglion (SG), stria vascularis (StV) and spiral ligament (SpL). The bracket and double head arrow indicate the thickness of the stria vascularis and the spiral ligament, respectively. (J, L, N) Higher magnification of the organ of Corti in Irs2+/+Ptpn1+/+, Irs2−/−Ptpn1+/+ and Irs2−/−Ptpnr−/− mice at postnatal wk 11 illustrating that the outer hair cells (OHC) and inner hair cells (IHC), as well as the surrounding supporting cells, were normal in appearance in both mutants (L, N) compared with the control wild-type mice (J). (K, M, O) Myosin VIIa expression in the inner hair cells (IHC) and outer hair cells (OHC) was unaffected in both mutants (M, O). Scale bars: A, B, D–F, 500 µm; G–I, 100 µm; J–O 25 µm.