MAIN LAYERS OF THE EPIDERMIS AND THE PROCESS OF KERATINIZATION

Abstract

The epidermis, the outermost layer of the skin, serves as a vital barrier between the body and the environment. This article reviews the structure and function of the epidermis, with particular emphasis on its major layers—the basal layer, spinous layer, granulosa layer, stratum lucidum (in thick layers of the skin), and stratum corneum—and their role in the keratinization process. Keratinization is a vital process in which keratinocytes mature and transform into corneocytes, providing a protective, waterproof barrier against mechanical stress, dehydration, and pathogenic microorganisms. This review describes the step-by-step process of keratinocyte differentiation, beginning with their proliferation in the basal layer and ending with their final exfoliation in the outermost layer. The molecular mechanisms regulating this process are discussed in detail, including
the expression of keratin proteins and the formation of the lipid barrier. Understanding the
keratinization process and the structure of the epidermal layers is crucial for understanding
various skin diseases such as psoriasis, eczema and other diseases
associated with impaired skin barrier function.