Immunohistochemistry of NOS subtypes in cochlea. Immunohistochemistry of cochlear nNOS (A,B), eNOS (C,D) and iNOS (E,F) expression in the control NBA and HBOT groups. (G) Spleen tissue was used as a positive control for iNOS. (H) Schematic drawing depicting a cross-section through cochlear canals and its related sub-structures. (A,B) nNOS immunoreactivity was present in the spiral ganglion, stria vascularis, organ of Corti, limbus and modiolar nerve bundles in both groups but enhanced immunoreactivity was present in the HBOT group. (C,D) eNOS immunoreactivity was found in the modiolar blood vessels, stria vascularis, organ of Corti, limbus and spiral ganglion in both groups with more enhanced immunoreactivity in the HBOT group. iNOS did not exhibit immunoreactivity in the control NBA (E) and HBOT (F) groups, as compared with the positive control of iNOS expression in the spleen tissue (G). Scale bar, 50 μm.