Morphological character of crystalline components present in saiga horn.

The purpose of this study was to investigate the ultrastructure of saiga-antelope (Saiga tatarica) horn for proposing the mechanism of the initial mineralization. Horn is derived from horny tooth of Cyclostomata. The minerals in saiga horn were identified crystallographically using electron microscopy and X-ray diffraction techniques. Soft X-ray photographs revealed the degree of the mineralization pattern. However, the number of rings did not indicate the age of saiga. Mineral deposites were observed among well banded keratin fibers and composed of powder like crystals. This deposited crystals were found by the X-ray diffraction method to be octacalcium phospate (OCP) by comparing these periodic lattice fringes to JCPDS card data. The chemical formula of OCP is Ca8H2(PO4)6.5H2O. Evidences for the presence of OCP in mature hard tissues have never been obtained. This phenomenon described here may be characteristic of saiga horn because we have found no reports on this type of OCP mineralization in any other animal species. It is possible that OCP is the precursor in the initial mineralization step, indicating in a nucleation of mineral on the keratin fibers.