Development of the giraffe horn and its blood supply.

The giraffe horn is an unusual cranial exostosis that lacks clear delineation and categorization as either horn or antler. The distinction between the two is made by contrasting their methods of development and basic composition. This process of development has not been detailed in the giraffe, a factor contributing to the difficulty in distinguishing the classification of these horns. In a chronological series of giraffe horns from prenatal and postnatal animals, we have observed unique morphologies that define their proper location on the skull, the blood supply to them, and the transitions involved in their histological development. While our observations have facilitated the classification of the giraffe horn, our interpretations were not always in accord with previous reports.