PHENOLIC OXIDATIVE ACTIVITIES OF THE SKIN: SOME REACTIONS OF KERATOHYALIN AND TRICHOHYALIN

Open Access
Publisher Website
Google Scholar
Abstract
The epidermis and its adnexa exhibit several oxidative activities against phenolic derivatives. Of these the dopa-tyrosinase system is localized at the presumed sites of cutaneous melanogenesis, the central cells of the bases of the hair follicles and the Langerhans cells of the epidermis and margins of hair follicles. Activity against p-aminodimethylaniline is localized in hair medulla and sheath cells. Activity against carechol, pyrogallol, hematoxylin (without so-called mordants) and brazilin is localized in keratohyalin granules, the superjacent "eleidin" zone of the stratum corneum and in the trichohyalin granules. The first of these activities, the dopa oxidase reaction, is inhibited by millimolar cyanide, sulfide or azide, the other two are not inhibited by 0.01 [image] solutions of these reagents. Sodium hydrosulfite (m[image]) inhibits all three, cysteine the two latter. The polyphenol oxidative activity of the strongly eosinophilic trichohyalin granules is largely inhibited by formaldehyde fixation but resists hot methanol chloroform fixation and paraffin imbedding. Keratohyalin reacts much more rapidly on the polyphenols than trichohyalin. The reactivity resists formaldehyde as well as hot methanol chloroform fixation and withstands paraffin imbedding. These two polyphenol activities are much weaker in frozen sections of unfixed or 1 hour formalin fixed material, but if the same material is then postfixed and imbedded in paraffin, the full activity is exhibited, indicating the presence of a labile inhibitor. The p-amino-dimethylaniline reaction also resists formaldehyde or hot methanol chloroform fixation and paraffin imbeeding. The dopa tyrosinase activity requires unimbedded material which may be briefly fixed with formaldehyde. After methanol chloroform fixation keratohyalin is soluble in hot water and in warm normal HCl, in distinction from trichohyalin. Formaldehyde renders it resistant. Dilute hematoxylin and brazilin also color elastic fibrils and keratohyalin of rodent forestomach and esophageal epithelia. Hematoxylin gives deep blue coloration of formaldehyde-fixed enterochromaffin and eosinophil leukocyte granules, brazilin gave weaker and less definite colors.