Fig. 1

Immunohistochemical localization of chondroitin-sulfated proteoglycans (CSPGs) of the lectican family and hyaluronan and proteoglycan link protein 1 (HAPLN1) in cross-sections of the mouse cochlea. a and a′ The immunoreaction of the CSPG brevican (BCAN) was detected in a layer between the spiral ligament and the temporal bone and in the osseous spiral lamina between the spiral limbus and the auditory nerve. BCAN also appeared prominently at inner hair cells (IHC) (a′, magnification of white box in a). b and b′ Aggrecan (ACAN) labeling yields a strong immunosignal in the spiral limbus and partly in the spiral ligament. The magnification of the basilar membrane (b′, white box in b) reveals a weak staining of ACAN also at IHCs. c and c′ The immunohistochemical identification of neurocan (NCAN) resulted in a positive signal only at IHCs (c′, magnification of white box in c) while the rest of the cochlea seemed to be spared of NCAN. d and d′ HAPLN1 was detected in cochlear tissue in both the temporal bone and at IHCs (d′, magnification of white box in d). e Western blot analysis confirmed the presence of BCAN (~ 145 kDa full-length protein and 55 kDa fragment), ACAN (~ 450 kDa), NCAN (~ 150 kDa), HAPLN1 (~ 40 kDa), and HAPLN4 (~ 40–42 kDa) in the cochlear tissue of the mouse. Note that in a and a′, BCAN was labeled by a Cy3 secondary antibody. For better comparison the red color was switched to green. a–d and a′–d′ Maximum intensity projections of confocal stacks of cochlear cross-sections. a–d, scale 100 μm. a′–d′, scale 10 μm