Fig. 2.

Immunolabeling of P2Y₂, P2Y₄, P2Y₆, P2Y₁₂ receptors at P0. a P2Y₂ immunolabeling was detected in the both inner and outer hair cells in the great epithelial ridge, intraganglionic spiral bundle, spiral ganglion neurons and their nerve fibers innervating hair cells. b The distribution of P2Y₄ receptor included the marginal and intermediate cells of the stria vascularis, epithelial cells of the Reissner's membrane, both inner and outer hair cells in the greater epithelial ridge, fibrocytes in the spiral limbus and spiral ganglion neurons. d A close-up of P2Y₄ immunolabeling on the epithelial cells of the Reissner's membrane. f Weak P2Y₆ immunofluorescence was found in the greater epithelial ridge, both inner and outer hair cells and perinuclear region of spiral ganglion neurons. Strong expression of P2Y₆ receptor was constrained to the cuticular plates of inner and outer hair cells. g P2Y₁₂ protein expression was limited to the basal pole of inner and outer hair cells and the perinuclear region of spiral ganglion neurons. i P2Y₆ immunolabeling in the hair cells showed prominent expression in the cuticular plates of the hair cells. c, e, h, j Lack of immunolabeling in the negative controls, using pre-adsorption of the P2YR antibodies with respective target peptides demonstrated the specificity of these P2Y receptors protein expression. Scale barsa–c, e–h, and j 50 µm; d, i 20 µm. cp cuticular plate, ger greater epithelial ridge, ihc inner hair cells, igsb intraganglionic spiral bundle, o/C organ of Corti, ohc outer hair cells, rm Reissner's membrane, sb spiral limbus, sgn spiral ganglion neurons, sl spiral ligament, sv stria vascularis