Cell surface and cytoskeletal changes associated with epidermal stratification and differentiation in organ cultures of embryonic human skin

Abstract

Embryonic and fetal human epidermis differentiates in organ culture in an age dependent, though accelerated, manner. The older the specimen the less time is required for epidermal differentiation. Morphological markers of epidermal differentiation, including the different epidermal strata, keratohyalin granules, lamellar granules, and cornified cell envelopes, are formed in a manner that is faithful to development in vivo. The high molecular weight, “differentiation specific” (67 and 56.5 kDa) keratins are also expressed in these cultures, even in the absence of morphological evidence for keratinization. Unstratified, embryonic epidermis was found to stratify overnight in culture. The time course of cell surface changes, detected by lectin binding, and cytoskeletal changes, detected by expression of the high molecular weight keratins, was followed in these cultures. Peanut agglutinin (PNA) binding sites appeared overnight in culture coincidently with epidermal stratification while expression of the 67 and 56.5 kDa keratins was not detected until the third day of culture. The possible significance of these results is discussed.