THE CONNECTIVE TISSUE HISTOCHEMISTRY OF NORMAL AND SOME PATHOLOGICAL SKIN

Abstract

A detailed histochemical study of the connective tissue of the skin has been presented. The stains used included hematoxylin and cosin, Mowry's colloidal iron and alcian blue for acid mucopolysaccharides, bromphenol blue for proteins, synthetic orcein and Verhoeff's for elastic tissue, and a combined Mowry's colloidal iron-orcein stain. Blocking procedures employed included methylation, demethylation, acetylation, deamination, and oxidation. Enzyme extractions were performed with testicular hyaluronidase. Representative diseases of the following three types were studied: 1) those due to or influenced by the effects of solar radiation; 2) those associated with abnormal elastic fibers without particular relationship to the amount of actinic radiation; and, 3) those associated with large numbers of fibroblasts. In chronically sun-damaged skin such as actinic elastosis, actinic keratosis, and basal cell epithelioma, markedly increased amounts of acid mucopolysaccharides were found in the areas of basophilic and orceinophilic material. Polymorphic light eruption and discoid and disseminate lupus erythematosus were found to have numerous acid mucopolysaccharide strands throughout the upper one-half of the dermis. Elastosis perforans serpiginosa displayed increased acid mucopolysaccharides associated with its orceinophilic fibers. Approximately 75% of the acid mucopolysaccharide in sun-damaged skin and elastosis perforans serpiginosa was removed by testicular hyaluronidase. In pseudoxanthoma elasticum each curled elastic fiber was found in the center of a pool of acid mucopolysaccharide, as though, when it retracted, it brought its mucopolysaccharide sheath with it. This acid mucopolysaccharide, in contrast to that found in sun-damaged skin and elastosis perforans serpiginosa, is only slightly labile to testicular hyaluronidase. Acid mucopolysaccharides were also found in large quantity wherever there were young fibroblasts as in dermatofibromas, neurofibromas, keloids, and fibroepithelial polyps, and is believed by the authors to represent de novo production by these cells rather than "mucinous degeneration." Hyaluronidase removed approximately 75% of the acid mucopolysaccharides in all conditions associated with young fibroblasts. The usefulness of the combined Mowry-Haleorcein stain was stressed. From the evidence presented, doubt was cast on the presently held concept that colloidal iron binding is by dissociated acid groups alone; iron may also be chelated by the intermolecular hydrogen bond of acid mucopolysaccharides. Oxidation greatly increased the intensity of Mowry-Hale staining: bromine probably by direct bromination and formation of cysteic acid and permanganate probably by formation of carboxyl groups.