ABSTRACT
In the surface area of the skin, layers of corneocytes are tightly and stably bound to each other to form the stratum corneum (SC), the thin but tough barrier at the outermost area of the skin directly facing the external world. Each corneocyte originates from a keratinocyte which is actively proliferating in the epidermis under the SC, i.e., new layers of the corneocyte are supplied continuously from below the SC (Fig. 1). Concurrently, corneocytes serially detach and smoothly drop off from the skin surface for replacement to maintain the integrity and thickness of the SC, keeping it healthy. This shedding process of the corneocyte from the SC, desquamation, has strongly attracted the interest of many skin researchers because this is the process which regulates the condition of the skin.
