Antlers are made of true bone that is fed by blood which is carried in the outer velvet covering. Velvet antlers are hot to the touch, with brushy hair and a waxy feeling coating.
A buck in velvet is sensitive and extremely protective of his antlers. These bucks will not fight or spar with their antlers when still in velvet, and if provoked they will rise to strike with their just as deadly hooves instead. Watching a buck in velvet slipping through the woods, you will see him delicately turn to avoid brushing the branches with his antlers.
The growth cycle is regulated by testicular and pituitary hormone. Secretions from the pituitary initiate the growth in April or May. In the northern hemisphere increasing day length also plays a role. Early in their development, antlers have high water and protein content. As they grow, antlers are covered with skin and soft hair called velvet, which carries blood vessels and nerves.
As antlers near the end of the growing process, spongy bone in their outer edges is replaced by compact bone, while their centers become filled with coarse, spongy, lamellar bone and marrow spaces. The velvet dies and is removed in part by the animals rubbing and thrashing their antlers against vegetation. The antlers also are stained during this action, giving them the brown, polished, wooden look.
Males use their full-grown antlers during the breeding season in social interactions in competition for females. In winter, pituitary antler-growth hormone stimulation decreases as day length shortens, and androgen secretion lessens. As a result, the pedicel loses calcium, weakening the point of connection between it and the antler, and eventually the antlers are shed. Males then are without antlers for a few months in late winter until the cycle begins again. Curiously, some cervids have large canine teeth, which are used in sexual displays and fighting. Often species with large canines have small antlers or are missing antlers altogether.