Seasonal conditions determine the manner of skin rejection in reptiles

During summer, 33%, 52%, and 15% of lizards Chalcides ocellatus rejected first set skin allografts (time between day of first sign of rejection and end point), respectively in an acute (11–14 days), subacute (15–20 days), and chronic (21–24 days) manner. Second set grafts were rejected in an acute fashion (8–13 days). Examination of histological samples from grafted areas revealed evident lymphoid cell aggregations in allo‐ but not in autografts. This suggests that graft rejection results from an immunological reaction against allogeneic cells. In the other seasons, all skin allotransplanted lizards rejected the graft in a chronic manner: in 46–132 days during autumn, 31–79 days in winter, and 40–78 days during spring. These data indicate that graft rejection in reptiles is under the control of seasonal conditions.