Abstract. Oxytalan connective tissue fibers are a separate and distinct fiber type. Although current histochemical methods cannot distinguish pre‐elastic from oxytalan fibers, the two fiber types are readily distinguished by electron microscopy. Oxytalan fibers are found in periodontal membranes of all teeth of man, monkeys, rats, guinea pigs and mice. Increased numbers and size of oxytalan fibers are observed in periodontal membranes of teeth subjected to increased stress, such as those used for bridge abutments. Edwards (1968) observed increased size and number of oxytalan fibers in periodontal membranes of dog incisors subjected to orthodontic forces. Some oxytalan fibers serve to support the blood and lymphatic vessels leading to the teeth. Oxytalan fibers appear to have a protein component and a stainable component digestible with β‐glucuronidase after peracetic acid digestion. Oxytalan fibers develop in repair tissues of the periodontal membrane. Although oxytalan fibers probably develop in relation to tumors developed from dental tissues, electron microscopy must be employed to distinguish oxytalan from developing elastic tissues inasmuch as histochemical methods are inadequate.

No abstract

A collagenase, operative at neutral and alkaline pH, has been extracted from the granule fraction of human granulocytic leukocytes. It digests reconstituted collagen fibrils and reduces the viscosity of collagen solutions. Cleavage of collagen in solution with purified enzyme produces the discrete products characteristic of other animal collagenases.

A B S T R A C T This report suggests a mechanism for collagen degradation mediated by human granulocytic leukocytes. A specific collagenase, which is extractable from human granulocytes, has been partially purified by DEAE chromatography. This collagenolytic enzyme is operative at physiological pH and is inhibited by EDTA, cysteine, and reduced glutathione but not by human serum. The enzyme cleaves the collagen molecule into two specific products, without loss of helical conformation. Electron micrographs of segment long spacing aggregates indicate that the cleavage occurs one-quarter of the length from the carboxy terminal end of the molecule. Experiments with crude extracts from granulocytes suggest that the specific products of granulocyte collagenase activity are then degraded by other proteases present in the human granulocyte.