Early fine structural changes in human epidermis following application of croton oil

Early epidermal changes in human subjects following application of 10% croton oil in acetone were studied by electron microscopy. The prominent changes observed at 1 and 5 hours were degeneration of epidermal cells and intercellular edema in the basal and spinous layers. One type of degeneration was homogenization and aggregation of the tonofilaments of keratinocytes at 1 hour, which may explain the presence of dyskeratotic cells at 5 hours. Another type was of a cytolytic nature as evidenced by severe perinuclear edema of keratinocytes and destruction of Langerhans' cells with outpouring of Birbeck's granules in the intercellular spaces.