Ultrastructural histochemistry of the surface lamina of normal articular cartilage

Abstract

Two collagen-poor, ultramicroscopic layers are described at the surface of canine articular cartilage. They are distinguished by staining with an electron-dense cationic dye, Cupromeronic Blue, in a critical electrolyte concentration technique and by digestion with testicular hyaluronidase. The superficial layer, approximately 50 nm thick, stained at low electrolyte concentrations but failed to stain in conditions specific for sulphated glycosaminoglycans. It was hyaluronidase-resistant and may be either glycoprotein or protein in nature. The deeper layer, 100-400 nm thick, stained positively at electrolyte concentrations specific for sulphated glycosaminoglycans but not in conditions specific for keratan sulphate. It was removed by hyaluronidase digestion. This layer probably represents a chondroitin sulphate-rich proteoglycan. These surface layers may be important in the lubrication of the articular surface and in the permeability and compression resistance of the superficial cartilage zone.

Light and electron microscopic morphology of the temporomandibular joint in growing and mature crab-eating monkeys (Macaca fascicularis): the condylar articular layer

“…Furthermore, in contrast to the results of Appleton (1975) in 20-and 80-day-old rats, our data do not suggest a significant influence of maturation on the thickness of the surface lining. On the other hand, a bi-layered lining was also observed on our own preparations of hyaline articular cartilage, as well as on specimens fixed in the presence of cupromeronic blue (Orford and Gardner 1985). Thus, our findings indicate that the lining on condylar articular surfaces is similar to that in other synovial joints, although condylar articular tissue differs considerably from articular cartilage.…”

“…Neither the fuzzy coat nor the granules of the articular surface lamina could, however, be identified in the SEM. Rather, articular surfaces appeared to be formed by larger globules which constituted a true "lamina obscurans" (Orford and Gardner 1985) in load-bearing regions, but did not completely obscure collagen fibrils in non-load-bearing regions. Therefore, we consider these globules representations of the articular surface lamina, and assume that the granules observed in the TEM clumped together during critical point drying, while the fuzzy coat was beyond the resolution of the SEM.…”

Effect of Mechanical Load on Articular Cartilage Collagen Structure: A Scanning Electron-Microscopic Study

“…The bulging edge has been described in the literature and is thought to be composed of an amorphous material without a collagen fibril network and probably due to large globular glycoproteins precipitated from the synovial fluid [Maroudas, 1976;Orford and Gardner, 1985;Kobayashi et al, 1995Kobayashi et al, , 1996. In our study the bulging edge was visible only under highforce and long-duration load and appeared at higher magnification to be composed more of a fibrillar structure than an amorphous structure.…”

The surface contour of articular cartilage in an intact, loaded joint

“…Current knowledge of these larger irregularities has been thoroughly reviewed by Gardner & McGillivray (1971) and, more recently, by Bloebaum & Radley (1995). A second type of roughness includes much smaller irregularities visible by TEM at magnifications between 5000 and 60 000 times (Silberberg et al 1961 ;Barnett et al 1963 ;Weiss et al 1968 ;Bullough & Goodfellow, 1971 ;Stanescu & Leibovitch, 1982 ;Jurvelin et al 1985 ;Laver-Rudich & Silbermann, 1985 ;Orford & Gardner, 1985). At these magnifications, the surface usually appears rough and this roughness increases with age and\or degeneration.…”