Histochemical Characterization of the Rat Ossicular Joint Cartilage with a Special Reference to Stapediovestibular Joint

抄録

The stapes footplate articulates the vestibular window (stapediovestibular joint; SV joint). The SV joint is known as crucial region of otosclerosis. To shed a light on pathogenesis of otosclerosis, we have examined the histochemical characteristics of the rat ossicular joint cartilage. Interestingly, glycoconjugate histochemistry revealed that the cartilage matrix components of the SV joint were significantly different from those of the other ossicular joints, i.e. incudomalleolar (IM) and incudostapedial (IS) joints. Alcian blue, pH 2.5 and high-iron diamine procedures vividly stained the cartilage matrices of the IM and IS joints, while those of the SV joint were faintly stained. Chondroitin sulfate immunohistochemistry revealed intense labeling of the cartilage of the IM and IS joints, while the immunolabeling of the SV joint was negligible. On the contrary, keratan sulfate immunolabeling was discernible on the cartilage matrices of the SV joint, but not on those of the IM and IS joints. Type II collagen immunolabeling revealed that the marginal region of the IM and IS joint cartilage matrices was devoid of the immunostaining, while the SV joint cartilage matrices were uniformly labeled with this antibody. In this study, we have succeeded in demonstrating the histochemical characteristics of the rat SV joint cartilage matrices of which is quite different from those of the other ossicular joints.