The organization of collagen in cryofractured rabbit articular cartilage: A scanning electron microscopic study

Abstract

Adult rabbit articular cartilage was prepared for scanning electron microscopy using, in order, glutaraldehyde fixation, enzymatic removal of proteoglycan, dehydration in ethanol, cryofracture in liquid nitrogen, and critical-point drying. Enzymes were effective in fixed material. Fixation, cryofracture, alignment of fracture surfaces with "split lines," and retention of subchondral bone were found to be necessary steps for the preservation of collagen detail. The fibrous framework was found to be similar to that proposed by Benninghoff and favored by more recent phase-contrast microscopic studies. Vertical fibers extending from subchondral bone and a network of tangentially oriented superficial fibrils converge in the transitional zone. No random layer is seen. Pericellular capsules interdigitate with the vertical fibers. When cartilage is prepared in a manner that minimizes tissue damage, scanning electron microscopy provides useful, unique information.

The effect of detachment of the articular cartilage from its calcified zone on the cartilage microstructure, assessed by 2H‐spectroscopic double quantum filtered MRI

“…The two "gold standards" for deducing collagen fiber architecture are scanning electron [4,15,16,30] and polarized light microscopy [48]. However, these methods involve fixation, decalcification, dehydration, and sectioning, and the measurement of the effects of pressure has to be performed on a series of plugs, each at a different pressure.…”

“…In the intermediate zone, the fibers bend and then align parallel to the surface. The thickness of the collagen fibers is largest near the bone and decreases continuously towards the surface [4].…”

“…Articular cartilage can be divided into zones, which differ in the relative amounts of cartilage constituents and in the orientation of the collagen fibers. The collagen fibers are anchored to the underlying bone, which has been shown to greatly support the collagen fiber matrix [4,14]. They rise vertically from the bone and keep the same orientation throughout the calcified and radial zones [ 15,16,30].…”

Multinuclear NMR and microscopic MRI studies of the articular cartilage nanostructure

“…In the intermediate zone, the fibers bend and then flatten in the superficial zone, where they are aligned parallel to the cartilage surface. The thickness of the collagen fibers is largest near the bone and decreases continuously towards the surface (5). The collagen fibers are anchored to the underlying bone, which has been shown to support the collagen fiber matrix (5,6).…”

“…The thickness of the collagen fibers is largest near the bone and decreases continuously towards the surface (5). The collagen fibers are anchored to the underlying bone, which has been shown to support the collagen fiber matrix (5,6). In the calcified zone, near the bone, the cartilage is heavily impregnated with calcium in the form of hydroxyapatite crystals (7).…”