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

Published online by Cambridge University Press:  13 September 2016

Saeed Akhtar ,
Mousa Alkhalaf ,
Adnan A. Khan  and
Turki M. Almubrad
Saeed Akhtar*
Affiliation:
Cornea Research Chair, Department of Optometry, College of Applied Medical Science, King Saud University, PO Box 10219, Riyadh 11433, Saudi Arabia
Mousa Alkhalaf
Affiliation:
Cornea Research Chair, Department of Optometry, College of Applied Medical Science, King Saud University, PO Box 10219, Riyadh 11433, Saudi Arabia
Adnan A. Khan
Affiliation:
Cornea Research Chair, Department of Optometry, College of Applied Medical Science, King Saud University, PO Box 10219, Riyadh 11433, Saudi Arabia
Turki M. Almubrad
Affiliation:
Cornea Research Chair, Department of Optometry, College of Applied Medical Science, King Saud University, PO Box 10219, Riyadh 11433, Saudi Arabia
*
*Corresponding author. akhtars@ksu.edu.sa
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Abstract

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.

Keywords

dhub lizardUromastyx aegyptialamellaeproteoglycanscollagen fibriltomography
Type
Biological Applications
Information
Microscopy and Microanalysis , Volume 22 , Issue 4 , August 2016 , pp. 922 - 932
Copyright
© Microscopy Society of America 2016 

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