Future directions in antler research.

Through a series of interrogatories, unsolved problems of antler evolution, anatomy, development, physiology, and pathology are probed, with commentaries, on the following prospects for future research: 1. How could these improbable appendages have evolved mechanisms to commit suicide, jettison the corpse, and regenerate new ones every year? 2. By what developmental processes are antlers able to prescribe their own morphogenesis with mirror image accuracy year after year and in some cases produce deliberate asymmetries? 3. What causes the scalp to transform into velvet skin as a deer's first antlers develop? 4. Why do healing pedicle stumps give rise to antler buds instead of scar tissue? 5. How is the unprecedented rate of antler elongation related to the diameter and length of the structure to be grown? 6. How come wound healing by pedicle skin is held in abeyance for several months until new growth resumes? 7. How is it that tropical deer regenerate antlers at any time of year, while in temperate zones deer do so in seasonal unison? 8. How do deer find enough calcium to make such massive antlers in only a few months? 9. What is the nature of the bizarre tumors that some antlers grow following castration?