Les yeux des serpents et de la plupart des geckos sont protégés par une couche de peau transparente (la lunette précornéenne), dont la couche externe consiste en une écaille transparente sur le plan optique. Expression of β-keratins in the spectacle has clearly evolved for needs specific to this specialized region of the integument. Other findings include a greater β-keratin to α-keratin ratio in the embryonic spectacle of pythons compared with those from after hatch and a complete absence of β-keratin in gecko spectacle scales, an unusual characteristic for squamate integument. Results indicate that the spectacle scale of snakes differs in the types of β-keratins it contains and that diversity in spectacle β-keratins occurs between species and bears a relationship with taxonomy, suggesting that optical transparency is not restricted to a few isoforms.
The composition of the spectacle scales of numerous snakes and two geckos was analyzed with particular focus on β-keratins, the hard proteins that form the outermost layer of squamate scales, to determine whether spectacle scales differ biochemically from other scales and whether they differ between species. The characteristics of the spectacle scale that contribute to its transparency are not well understood but may conceivably be related to its biochemical composition.
Snake spectacle skin#
The eyes of snakes and most geckos are shielded beneath a layer of transparent skin (the “spectacle”), of which the outermost layer consists of an optically transparent scale.
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