title: Keratinization.
abstract: Early studies have already shown that the tonofibrils of malpighian cells consist of a --SH containing fibrous alpha-protein. It was assumed that the highly resistant protective substance, keratin, was formed by the conversion of --SH groups into --S--S--bonds in this protein. This chemical reaction was regarded as the most significant event of the keratinization process. Recent studies show that keratinization proceeds by a synthetic and a degradative stage and that ultimately a complex protective substance is formed. Horny cells become filled with --SH-containing filaments embedded in a --S--S---rich amorphous matrix. This complex is encased by a thickened membrane rendered insoluble by --S--S bonds and an unknown, highly resistant bond. In the stratum corneum, the intercellular space is occupied by bipolar lipids originating from the discharged lamellae of membrane-coating granules.
mesh_terms: D000818:Animals; D003594:Cytoplasmic Granules / Q000378:metabolism; D004220:Disulfides / Q000096:biosynthesis; D006801:Humans; D007633:Keratins / Q000096:biosynthesis*; D012867:Skin / Q000378:metabolism* / Q000648:ultrastructure; D013438:Sulfhydryl Compounds / Q000378:metabolism
chemical_list: D004220:Disulfides; D013438:Sulfhydryl Compounds; D007633:Keratins