Answer:
A full thickness skin biopsy is taken and then mechanically and enzymatically broken up into separate individual epithelial cells. This suspension of cells is plated onto culture media containing fetal calf serum, insulin, transferrin, hydrocortisone, epidermal growth factor, and cholera toxin. The media overlies a layer of murine fibroblasts which facilitates clonal expansion. The epithelial cells grow into broad sheets of cells which are then enzymatically broken up and then re-cultured using the same techniques. The subsequent sheets of epithelial cells are removed from the dishes using dipase which digests protein attachments between the cells and the culture dish. The sheets are placed on petrolatum gauze to faciliate handling.