Ultrastructural modifications of cartilage matrix treated with guanidinium HCl (4.0 M and 0.4 M)

Significative modifications in cartilage matrix are induced by GuHCl 4 M and 0.4 M treatment. The first treatment (4 M) induces a complete lack of interfibrillar alcianophilic particles and the swelling of collagen fibrils in 8 nm (80 A) thin aperiodic microfilaments. Among microfilaments, come alcianophilic sheets are often present ( unextractable proteoglycans?). The rectilinear pattern of filaments inside the fibrils became helicoidal. The second treatment (0.4 M) does not modify the interfibrillar morphology of alcianophilic rod like particles but may swell collagen fibril. Aldehydic fixation completely prevents such modifications. These observations show that organization of periodic collagen fibrils is probably due to proteoglycans also.