Fig. 1From: Immunological challenges associated with artificial skin grafts: available solutions and stem cells in future design of synthetic skinAllorecognition pathways: Direct pathway is the process whereby the donor’s MHC molecules on APCs is recognized by the TCRs of recipient’s T cells. Indirect pathway recognizes the processed peptide presented by recipient’s MHC on APCs. Semi-direct pathway is where T cell activation occurs by transfer of the donor’s MHC onto the recipient’s APCsBack to article page