I came across a neat article in Scientific American that described how reindeer and elk regrow their antlers every year. Could you imagine putting that much energy into growing new bone each year complete with a velvety cover containing nerves, skin, and blood vessels? Although full-grown antlers lose their blood supply and animals scrape the velvet layer off to reveal just bone.
Researchers have explored whether understanding this amazing process of annual antler regeneration could lead to new therapies to regrow nerves or organs in humans. The nerve fibers that innervate the antlers in deer originate from the trigeminal nerve. These sensory fibers grow at an impressive rate of up to 2 cm every day! The nerves are located in the velvet that covers the external surface of the antlers and they are closely associated with skin and the blood supply, which gives them access to nutrients and molecules that can help guide their growth. The cartilage and bone are found internally. The antlers grow annually from a base of sorts, called the pedicle. The pedicle is a permanent growth on the frontal bone which has been found to contain stem cells that are responsible for creating the internal components of the antlers. It is thought that the external components, including the blood supply and nerves are stimulated to grow by chemical signals and perhaps mechanical cues from the growth of the internal components. Dr. Li from the AgResearch Invermay Agricultural Center in New Zealand, has suggested that identifying these chemical signals may lead to new discoveries in organ regeneration for humans.
To learn more about how these animals regrow antlers, check out this video:
Li C. Deer antler regeneration: A stem cell-based epimorphic process. Birth Defects Research C Embryo Today. 96(1): 51-62, 2012.
Nieto-Diaz M, Pita-Thomas DW, Munoz-Galdeano T, Martinez-Maza C, Navarro-Ruiz R, Reigada D, Yunta M, Caballero-Lopez MJ, Nieto-Sampedro M, Martinez-Maza R. Deer antler innervation and regeneration. Frontiers in Bioscience. 17:1389-1401, 2012.