Fig. 4.

Changes in circulating concentrations of testosterone and the carboxy-terminal pro-peptide of type I collagen (PICP) during the antler growth cycle in red deer stags. Serum samples were collected at post-mortem from deer stags killed for venison at different times of year. PICP was measured by radioimmunoassay (Orion, Diagnostica, Finland) and the values shown are the mean ± SEM. This illustrates that antler regeneration is associated with significant changes in bone turnover. The testosterone graph is adapted from Muir et al. (1988).