NORMAL HUMAN KERATINIZATION PROCESSES AS DEMONSTRATED BY ELECTRON MICROSCOPY

[摘要] The horny cell is shown to be formed by a binding together of filaments in an electron-dense, sulfur containing, cement substance. The filaments are present in the basal layer (approximately 50 A) and gradually increase in diameter (approximately 100 A) as the cell nears the surface. Keratohyalin is laid down and binds the filaments together thus forming compact bundles. The following points are important and have been described and emphasized. (1) Tonofilaments are present in the basal cells of the epidermis. These filaments on cross section are unstained and coated by an osmiophilic material. (2) In skin, keratohyalin material is necessary for keratinization to occur. With the electron microscope a transitional cell layer is occasionally seen between the stratum granulosum and stratum corneum. The cytoplasm of these cells is packed with keratohyalin granules. (3) The cytoplasm of the cells of the stratum corneum is composed of an irregular arrangement of unstained filaments embedded in a sulfur-containing matrix. (4) The cell membrane and desmosomes change radically as the cell keratinizes and these changes are described.