Collagen heterogeneity and quantification in developing bovine nuchal ligament.

The collagenous components were investigated in peptic digests of developing bovine nuchal ligament. Types I and III collagen were the major species isolated, but the presence of types IV, V and VI was also shown. Changes in the pepsin-susceptibility of nuchal ligament during foetal development were observed. CNBr-cleavage peptide analysis indicated that type I collagen became cross-linked rapidly, as evidenced by the lack of alpha 1(I)CB6. At present it is not clear if this decrease in pepsin-susceptibility is due to cross-linking of collagen, to increased deposition of elastin, or to both. Quantification of collagen types I and III was shown to depend on the method used. When pepsin-solubilized material was examined an apparent increase in type III collagen with respect to foetal age was observed, whereas when CNBr digests of intact ligament were examined a relatively constant amount of type III collagen (approx. 24%) was found. The constant amount of type III collagen observed during foetal development changed at birth and increased in mature nuchal ligament to represent approx. 45% of the total collagen.