Ultrastructure Features and Three-Dimensional Transmission Electron Tomography of Dhub Lizard (Uromastyx Aegyptia) Cornea and Its Adaptation to a Desert Environment

We report ultrastructural features and transmission electron tomography of the dhub lizard (Uromastyx aegyptia) cornea and its adaptation to hot and dry environments. Six corneas of dhub lizards were fixed in 2.5% glutaraldehyde and processed for electron microscopy and tomography. The ultrathin sec...

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Bibliographic Details
Published in:Microscopy and microanalysis 2016-08, Vol.22 (4), p.922-932
Main Authors: Akhtar, Saeed, Alkhalaf, Mousa, Khan, Adnan A., Almubrad, Turki M.
Format: Article
Language:English
Subjects:
Adaptation, Physiological
Animals
Biological Applications
Cornea
Cornea - ultrastructure
Desert Climate
Deserts
Electron Microscope Tomography
Endothelium
Lacertilia
Light
Lizards
Proteins
Proteoglycans - chemistry
Reptiles & amphibians
Retina
Tomography
Water content
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Summary:We report ultrastructural features and transmission electron tomography of the dhub lizard (Uromastyx aegyptia) cornea and its adaptation to hot and dry environments. Six corneas of dhub lizards were fixed in 2.5% glutaraldehyde and processed for electron microscopy and tomography. The ultrathin sections were observed with a JEOL 1400 transmission electron microscope. The cornea of the dhub lizard is very thin (~28–30 µm). The epithelium constitutes ~14% of the cornea, whereas the stroma constitutes 80% of the cornea. The middle stromal lamellae are significantly thicker than anterior and posterior stromal lamellae. Collagen fibril (CF) diameters in the anterior stroma are variable in size (25–75 nm). Proteoglycans (PGs) are very large in the middle and posterior stroma, whereas they are small in the anterior stroma. Three-dimensional electron tomography was carried out to understand the structure and arrangement of the PG and CFs. The presence of large PGs in the posterior and middle stroma might help the animal retain a large amount of water to protect it from dryness. The dhub corneal structure is equipped to adapt to the dry and hot desert environment.
ISSN:1431-9276
1435-8115
DOI:10.1017/S1431927616011466