Long-term organ culture of human skin: an ultrastructural and immunochemical study

Human skin grown in tissue culture medium for periods of up to 18 wk undergoes characteristic morphological changes. After an initial period of degeneration, new foci of epidermal cells arise at the dermo-epidermal junction and by rapid proliferation these cells spread out to form a complete second epidermal layer beneath the degenerating original strata. Stratification occurs in this new epidermis with incomplete keratinisation. The individual keratinocytes show ultrastructural similarities with fetal cells. There is a loss of complexity of the cytoplasm typified by a marked reduction in the numbers of keratin filaments and a decrease in the numbers of desmosomal contact areas. In addition, the formation of cilia and accumulation of glycogen in the cell cytoplasm are characteristic. The cytoplasm of the basal cells contains numerous polyribosomes and there is evidence of synthetic activity as illustrated by the proliferation of rough-surfaced endoplasmic reticulum and Golgi complex. Fluorescent and EM immunocytochemical staining with an anti-fetal antiserum demonstrates the development of fetal substances on the surface of cells during the regeneration stage occurring in the cultured skins. The significance of these observations concerning transplantability of cultured tissues is discussed.