Delayed ectopic antler growth and formation of a double-head antler in the metacarpal region of a fallow buck (Dama dama L.) following transplantation of antlerogenic periosteum.

Autologous transplantation of antlerogenic periosteum to the metacarpal region of a fallow buck resulted in the formation of an ectopic pedicle within a few months after transplantation. In the following years the pedicle increased in size, but no ectopic antler development occurred. However, in the ninth year after transplantation a first antler of about 3 cm length grew from the ectopic pedicle. The hard ectopic first antler was not cast, and renewed antler growth, starting in late spring of the following year, led to the formation of a larger subsequent antler of 7.3 cm length. The latter exhibited a distal flattening (palmation) and a rudimentary basal coronet, thereby displaying morphological features typical of the subsequent antlers of fallow bucks. The results of the experiment indicate (1) that transformation from pedicle to antler growth can occur several years after pedicle initiation, when the pedicle has reached a certain threshold size, (2) that species and age specific features of antler morphology tend to be realized even in ectopic locations, and (3) that primary and subsequent antler growth was apparently triggered by cells of the pedicle periosteum, being derived from the transplanted antlerogenic periosteum. The findings thereby emphasize the importance of local factors in the control of pedicle/first antler transformation and antler morphogenesis.