The low molecular weight collagen synthesized by chick tibial chondrocytes is deposited in the extracellular matrix both in culture and in vivo.

The low mol. wt. collagen (64 K) synthesized by chick embryo chondrocytes in culture is deposited in the extracellular matrix; its deposition is strictly dependent upon a correct hydroxylation. In vivo the 64 K collagen has been isolated from the cartilage of tibiae obtained from 17-day-old chick embryos. The turnover of this collagen in the extracellular matrix is very rapid: within a few hours it is matured into a 30-K fragment released in the medium. Also this maturation is dependent upon a correct hydroxylation of the molecule. The underhydroxylated form, synthesized in the absence of ascorbic acid or in the presence of alpha-alpha' dipyridyl, is not deposited in the extracellular matrix and is directly secreted as 64 K collagen in the culture medium.