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

Abstract

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.

Gentamicin administration on the stapes footplate causes greater hearing loss and vestibulotoxicity than round window administration in guinea pigs

“…By way of contrast, the stapediovestibular joint (SVJ) in guinea pigs comprises hyaline cartilage on the articulating surfaces of the stapes footplate rim and OW frame, a fluidic articular cavity, and epithelial membranes with tight junctions overlying the structure (middle ear mucosa) as shown in Figure 7. In rats, mice and humans, the stapes is attached to the perimeter of the OW by an annular ligament (Ohashi et al, 2005; Ohashi et al, 2006; Okumura & Iwai-Liao, 1993). The annular ligament consists of a loose thin lattice-like structure of elastic and collagen fibers embedded within a central amorphous substance (Ohashi et al, 2005).…”

“…In rats, mice and humans, the stapes is attached to the perimeter of the OW by an annular ligament (Ohashi et al, 2005; Ohashi et al, 2006; Okumura & Iwai-Liao, 1993). The annular ligament consists of a loose thin lattice-like structure of elastic and collagen fibers embedded within a central amorphous substance (Ohashi et al, 2005). The interosseous elastic ligament fibers penetrate the cartilaginous tissues of the frame of the OW and the rim of the stapes footplate and a mantle of fine microfibrils and collagen fibers traverse these elastic fibers (Ohashi et al, 2005; Ohashi et al, 2006).…”

“…The annular ligament consists of a loose thin lattice-like structure of elastic and collagen fibers embedded within a central amorphous substance (Ohashi et al, 2005). The interosseous elastic ligament fibers penetrate the cartilaginous tissues of the frame of the OW and the rim of the stapes footplate and a mantle of fine microfibrils and collagen fibers traverse these elastic fibers (Ohashi et al, 2005; Ohashi et al, 2006). Without tight junctions present, substances would be expected to readily pass through it.…”

Mammalian middle ear mechanics: A review

“…Figure 5 shows the convex lenticular process of the mouse incus and the concave stapes head, forming the smallest joint of the body, the incudostapedial joint (ISJ) ( Karmody et al, 2009 ). It is a synovial joint with a joint capsule, cartilage, and synovial fluid ( Ohashi et al, 2005 ; Wang et al, 2006 ). Reported mechanical properties of the human ISJ included Young’s modulus in uniaxial tension and compression, stress relaxation, and failure tests.…”

Experimental measurement and modeling analysis on mechanical properties of incudostapedial joint

“…The incudostapedial (IS) joint connects the incus to the stapes and the stapes footplate sits on the oval window and contacts to fluid inside the cochlea. The IS joint is a synovial joint consisting of a joint capsule, cartilage, and synovial fluid as observed from histology (Ohashi et al 2005; Wang et al 2006) and scanning electron microscopy (SEM) of the middle ear (Djeric et al 1987; Ortug et al 2006; Karmody et al 2009). …”