Cochlear volumes. Volume (mean ± SEM, mm3) of the tympanic (ST), media (SM) and vestibular (SV) scalas and the spiral ligament (SpL), stria vascularis (StV) and cochlear ganglion (SG) in wild-type (n = 3), Irs2−/−Ptpn1+/+ (n = 4), and Irs2−/−Ptpn1−/− (n = 4) mice at 11 wks of age is shown. The smaller size of ST, SM and SpL in IRS2-deficient and double-null mice compared with wild-type mice did not reach significance. However, SG was significantly reduced in size in both IRS2-deficient (*P < 0.05) and double-null mice (##P < 0.01) compared with wild-type mice; StV also showed a decrease in volume, but only in IRS2-deficient mice (*P < 0.05; **P < 0.01). □, Irs2+/+Ptpn1+/+ mice; ■, Irs2−/−Ptpn1+/+ mice; ▥, Irs2−/−Ptpn−/− mice.