Keratinization process forming cell

Keratinization, the sloughing of epithelial cells in the hair follicle, is also a natural process. In acne, however, hyperkem-tinization occurs and causes increased adhesiveness of the sloughed cells. Accumulation of these cells clogs the hair follicle, blocks the flow of sebum, and forms an acne lesion called an open comedo or blackhead. ... 

Similar keratin filaments are found in hair. In a single wool fiber with a diameter of about 20 pm, millions of filaments are bundled together within dead cells. The individual keratin helices are cross-linked and stabilized by numerous disulfide bonds (see p. 72). This fact is exploited in the perming of hair. Initially, the disulfide bonds of hair keratin are disrupted by reduction with thiol compounds (see p. 8). The hair is then styled in the desired shape and heat-dried. In the process, new disulfide bonds are formed by oxidation, which maintain the hairstyle for some time. 

The skin is composed of two distinct but intimately associated layers of tissues, namely the epidermis and dermis (Fig. 1). The epidermis is further divided into the viable epidermis (a layer of stratified squamous epithelial cells in various stages of differentiation) and the stratum comeum (a layer of dead cells that form the outer layer of skin). In contrast to most tissues, the epidermis is in a state of flux. The cells at the surface of the skin are replaced continuously by cells migrating up from the lower levels of the skin in a process known by several names, including keratinization, comification, or differentiation. 

The structural and functional properties of the cutaneous surface almost entirely are those of the stratum comeum, modified only slightly by influences of hair, sweat glands and sebaceous glands. The process of keratinization, consisting of the aggregate events by which the epidermis forms the stratum comeum, must be reviewed not only in context with epidermal syntheses of fibrous proteins, mucopolysaccharides and special compounds that modify the texture of the stratum comeum but with other epidermal attributes such as rates of stratum comeum production, and cohesiveness of stratum comeum cells, their hydrophilic and water-binding properties, their elasticity and pliability. 

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