(A) Midmodiolar section of right implanted cochlea of case 3 with Iba1 immunostaining. The prevalence of Iba1-positive macrophages was evaluated in the organ of Corti, stria vascularis, and spiral ligament in five cochlear segments. A fibrous sheath enveloped the electrode track (*) within the scala tympani from lower to upper basal turns and the “sheath” boxed in black is shown in Fig. 2I. Four segments of the osseous spiral lamina are outlined in red. Three segments of Rosenthal’s canal are outlined in green boxes, each measuring 200×200 μm2.
(B) Upper basal turn of right implanted cochlea of case1 immunostained by Iba1. The organ of Corti (OC), stria vascularis (SV) and spiral ligament (SL) were degenerated. A fibrous sheath enveloped the electrode track (*) within the scala tympani. The boxed area near the habenula perforata is shown in the inset. A process of a macrophage (arrow) extended to the distal OSL.
(C) Higher magnification of the area of the middle RC by Normarski (different interference contrast) microscopy shown in Fig.1A. The counting frame was placed in the RC where the density of SG cells was highest. Some spiral ganglion cells (SG) were wrapped by macrophages.
(D) Midmodiolar section of right implanted ear of case 3 adjacent to the section shown in Fig. 1A with H&E staining. (D1): A higher magnification of the boxed area in OSL of lower middle turn. A few dark macrophage-like melanocytes (Mel) were shown. (D2): A higher magnification by Normarski microscopy. A melanocyte surrounded the small blood vessel (BV) in OSL (yellow arrow). The area of the “sheath” boxed in black is shown in Fig. 2H.
(E) Section of the modiolus of the implanted left ear of case 7 demonstrated the presence of melanocytes (Mel) with H&E staining.
(F) An adjacent sections to that shown in Fig. 1E with Iba1 immunostainning. Some Iba1-positive cells (P) may be melanocytes as shown in Fig. 1E.
(G) Macrophage phenotypes with Iba1 immunostaining. The amoeboid type has few processes, a relatively round cell body and a large nucleus. The ramified type has long and some branching processes. The transitional type displays intermediate morphology.