Organ culture of adult human skin.
Proliferation and differentiation of the epidermis in organ culture of adult human skin by the sponge matrix method were studied histologically and autoradiographically, and the following results were obtained: 1) On the first day of culture, mitotic figures were already observable in the epidermis. The outgrowth of epidermal cells at the margins of the explants started. On the second day, there was transformation to a zone that will be referred to as the newly formed stratum corneum in the upper epidermis. 2) On the third and fourth days, the increased growth of epidermal cells caused thickening of the epidermis. Simultaneously, Malpighian cells progressively differentiated into a cornified layer. 3) On and after the fifth day, the basospinous cell layer was reduced in thickness in most of explants. On the ninth and tenth days, DNA synthesis in the basal layer was still obvious, although the epidermis showed a thickness of only one or two cells overlaid with a large number of horny layers. 4) In the culture medium supplemented with corticosteroid, the epidermal growth was slightly depressed with lessened formation of stratum corneum in the early stages of culture as compared with the explants cultured in the basic medium. The reduction of the basospinous layer was scarcely notable after the fifth day. Even after 10-11 days, epidermal cells were well preserved and their stratified squamous architecture was less disorganized. It seemed that corticosteroid could prolong the survival of adult human skin in vitro. These findings indicate that this culture technique could be used as a model for organ culture of adult human skin.