The alleged traditional medicinal properties of rhinoceros horn resulted in a dramatic
escalation in rhinoceros poaching in South Africa. Despite the listing of all species of
rhinoceros in the International Union for Conservation of Nature Red List of threatened
animals, their numbers are still declining rapidly. Based on the assumption that rhinoceros'
horn consists of a collection of hollow tubules and intertubular hollow spaces, which allow
internal fluid distribution, a horn devaluation procedure through infusion of chemicals and
dyes was recently introduced. This procedure is costly and has a mortality risk. This study
provides the first detailed description of the development and resultant structure of the
rhinoceros horn. The unique solid structure which consists of a large number of tightly
packed filaments is the result of the cellular orientation of squamous epithelium corneocytes.
What was previously thought to be microtubules is an optical illusion created by the
orientation of the corneocytes in the solid filaments. We contest the scientific basis for
infusing chemicals into the rhinoceros horn as a deterrent for human use.