The physiological control mechanisms underlying the histogenesis of the pedicle, which precedes antler growth, from the frontal bones of male deer are poorly understood. The aim of this study was to investigate the extent of pedicle/antler regeneration after removal (for histological evaluation) of the antlerogenic region or pedicle tissue during pedicle development to determine whether the subsequent pattern of regeneration could contribute to the understanding of pedicle histogenesis and the mechanism of the transition between permanent pedicles and deciduous antlers. The contralateral pedicles of six stags were not removed and these data serve as controls. All deer were observed frequently and measurements of regeneration were made in March after all antler growth had ceased for that season. The development stage of the pedicle was determined by a combination of pedicle height measurements and histological studies. The results showed that pedicle formation histologically covers three stages: a period of intramembranous ossification (when the pedicle is less than 5 mm in height), a period when the ossification pattern changes (when the pedicle is between 5 and 28 mm in height) and a period of modified endochondral ossification (when the pedicle is over 30 mm in height). In all ossification stages some deer regenerated neither antlers nor pedicles. The pedicles which regenerated following the loss of antlerogenic tissue at the intramembranous ossification stage were shorter than the controls (P < 0.01), but longer than the pedicles regenerated after pedicle removal at the transitional stage in the pattern of ossification (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)