Maturation of normal human epidermis without an ordered structure

Whole mounts of epidermis were prepared from hamster and mouse ears and from three sites on six normal human volunteers. Corneocyte columns were sought visually with the light microscope and statistically with cluster analysis applied to the surface distribution of superficial nucleated keratinocytes. In fifteen consecutive fields of hamster and mouse epidermis, both cell columns and clustering of nuclei were detected. In eighteen consecutive biopsies from the forearm, back and thigh of six normal adult men, stacking was never seen and clustering could not be demonstrated statistically. Corneocyte columns do occur regularly in some mammalian species and they have been reported to occur in human skin, but such columns are not common in these sites from normal human skin. The stratum corneum of mammalian epidermis consists of multiple layers of flattened, anucleate corneocytes. At the skin surface these cells exfoliate, individually and in small aggregates, to the environment. This loss by exfoliation is balanced by proliferation and maturation of underlying nucleated keratinocytes (Bergstresser & Taylor, 1977). In cutaneous disorders such as psoriasis (Weinstein & Van Scott, 1965), or in response to environmental stresses such as tape stripping (Pinkus, 1951), retinoic acid application (Braun‐Falco & Christophers, 1969) or ultraviolet light irradiation (Epstein, Fukuyama & Fye, 1970) the rate of proliferation, maturation and exfoliation is greatly accelerated.