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| Location: |
World |
| Subject: |
Morphology - Horn |
| Species: |
All Rhino Species |
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Orientation of keratins. There is considerable confusion in the literature regarding the structure of rhinoceros horn and an attempt to clarify the position was made by Ryder. There is no doubt that, rhino horn consists of longitudinal filaments. These tend to separate, particularly at the proximal end, which no doubt, gave rise to the earlier statements that rhino horn is composed of matted hair (Anthony 1928, Beddard 1902). Although the latter is untrue, it has been shown that the inter-filamentous horn is much sparser than, for example, in the case of baleen plate, and the filaments are packed so tightly together that they are often multi-sided rather than circular. Morphologically, it is probably not incorrect to regard both baleen plate and rhino horn as intermediate between hair and cattle horn.
The microphotographs of transverse sections of individual filaments comprising rhino horn in Ryder (1962) show clearly longitudinal cell structures orientated tangentially in the plane of the section and were, in fact, very similar to sections of cat whisker.
The horns of 4 rhino species were available and a comparative investigation of these four keratins was made. The table suggests that Asian rhinos have horns superficially more resembling cattle horn than the African species, and R. unicornis being the only species containing apatite as a major constituent of its horn, it must be borne in mind that observations were made on a small number of animals.
,Macrostructure,Appearance in polarized light of transverse section,X-ray diffraction pattern
Rhinoceros unicornis ,General appearance like cattle horn, Filaments firmly embedded n matrix,Maltese-Cross effect,Poorly orientated a-pattern. Strong apatite reflexions
Rhinoceros sondaicus ,-do-,Patchy birefringence. Filaments too irregular to produce cross,poorly orientated a-pattern. Apatite reflexions absent
Diceros bicornis ,General appearance like bundle of bristles. Filaments readily separated.,Maltese-Cross effect,-do-
Ceratotherium simum
,-do-
,Patchy birefringence. Filaments too irregular to produce cross,-do-
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Molecular orientation of some keratins
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