Modifications of collagens in the course of inflammatory tracheal stenoses.

A comparison was made between the biochemical and histological properties of collagens contained in samples of normal tracheas obtained at autopsy or of stenosed tracheas obtained during surgery. The amounts of total collagen solubilized by pepsin was increased seven times in the pathological samples, and the proportion of cartilage type II collagen decreased by about one half, being replaced by type I collagen, whose ratio was increased five times. Microscopic studies confirmed that cartilage underwent a degenerative process and was progressively infiltrated by fibrils of interstitial collagen.