Oxytalan fibres in the human tympanic membrane

Oxytalan fibres in the periodontal ligament of equine molar cheek teeth

The distribution and arrangement of oxytalan fibres were examined in periodontal specimens of cheek teeth from seven horses. Oxidation prior to aldehyde fuchsin exposition permitted a selective staining of the oxytalan fibres, which are a distinct component of the elastic fibre system. On three horizontal levels of the periodontium--(a) subgingival, (b) middle third and (c) apical--two oxytalan fibre groups were shown histologically: 'blood vessel-related' and 'independent' oxytalan fibres. In levels a and b, both groups were arranged in a typical occluso-apical alignment along the reserve crown. Single oxytalan fibres deviated from their general course in order to attach to the cementum. In these cemental entheses the oxytalan fibres ran parallel to collagen fibre bundles. The interpretation of such morphological features emphasized the oxytalan fibres' capacity to improve the stability of periodontal blood vessel walls during masticatory movements. Level c, especially in regions next to the persisting epithelial root sheath, is the site of oxytalan fibre generation. This is a prerequisite for the facilitation of periodontal regeneration and reorganization during dental growth and eruption.

Tympanosclerosis, grommets and shear stresses

This paper deals with grommet induced tympanosclerosis. In the first part, patients from a controlled trial of the treatment of bilateral glue ear using unilateral grommet insertion are reviewed 15 years later. Tympanosclerosis due to grommet insertion is summated using computer graphics. Two areas of maximal tympanosclerosis are found, anteriorly and posteriorly midway between the annulus and the umbo. These maximal areas join inferiorly in the classical horse shoe shape. In an attempt to identify reasons for this distribution, the structure of the lamina propria is reviewed, and the changes that occur in tympanosclerosis considered. With this in mind, the tympanic membrane is modelled using finite element methodology to determine the areas of maximal shear stresses. These are found to be in the same position as tympanosclerosis. Such stresses would be increased by the weight of a grommet in situ. These stresses will damage the fibrils interconnecting between the fibrous layers of the lamina propria and this may lead to tympanosclerosis. This raises the question of whether a lighter grommet would decrease the incidence of grommet-induced tympanosclerosis.

Oxytalan fibers in peripheral odontogenic fibromas. A histochemical study of eighteen cases

Oxytalan fibers, identified by histochemical methods alone, were found embedded. Since oxytalan fibers have been found embedded in bone in the periodontal ligament, the finding of these fibers in the calcified material of peripheral odontogenic fibromas adds considerable weight to the assumption that these lesions are of periodontal ligament origin.

Light and ultrastructural relationship between oxytalan fibers in the periodontal ligament of the guinea pig

The interfaces and the relationships between collagen and oxytalan fibers were observed under light and electron microscopy. Guinea pig periodontal ligament was prepared for light and electron microscopy with perfusion using Peter's buffered formalin for light microscopy and GTA-S-collidine and OSO4 for electron microscopic studies. The tissue for light microscopy was stained with a modified Gomori's aldehyde fuchsin technique, in which pre-oxidization with potassium monopersulfate was carried out before staining so as to demonstrate the oxytalan fibers. EM tissues were routinely stained with lead citrate and uranyl acetate. Two different structural relationships were observed. First, the subcomponents of the collagen and oxytalan fiber types interweave with each other; and, second, some of these two-fiber subcomponents appear attached to each other. These relationships and the known orientation of oxytalan fibers as seen in the periodontal ligament provide insight as to the function of oxytalan fibers. The oxytalan fibers may provide increased structural integrity and increased distribution of forces over a wider area of the periodontal ligament. Because of their close relationship to blood and lymph vessels in the periodontal ligament, they may also help to stabilize these elements by the same structural relationships to collagen fibers.

Oxytalan fibre formation in the cornea: a light and electron microscopical study

Oxytalan is a fibrillar protein possessing some of the staining and ultrastructural properties of developing elastic tissue. In a study of human corneae we failed to find fibres of this type in five normal specimens but found them in each of 16 examples of keratoconus and 13 cases of post-traumatic or post-inflammatory scarring. In two cases the microfibrillar nature of the deposits was confirmed by electron microscopy, individual microfibrils measuring 10-12 nm in diameter and having profiles suggestive of a tubular structure. Oxytalan formation was intimately associated with the basal lamina of the covering epithelium with, in areas showing disruption of Bowman's layer and scarring, some extension into the superficial collagenous stroma.

Oxytalan connective tissue fibers: a review

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 beta-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.