Deer antlers are one of the fastest growing tissues we know of. Whitetails are capable of growing an inch or more of antler in a 24-hour period. Antler growth is governed by photo-periodism, or the amount of daylight reaching a buck's gland receptors. It's all part of the fall breeding cycle: testosterone builds, antlers harden, dominance is established and does get bred. Ain't it all grand?