Cornea Research Chair,Department of Optometry,College of Applied Medical Science,King Saud University,PO Box 10219, Riyadh 11433,Saudi Arabia.
Microsc Microanal. 2016 Aug;22(4):922-32. doi: 10.1017/S1431927616011466.
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.
我们报告 dhub 蜥蜴（Uromastyx aegyptia）角膜的超微结构特征和透射电镜断层扫描及其对炎热干燥环境的适应。固定了六只 dhub 蜥蜴的角膜，用 2.5%戊二醛进行处理，以进行电子显微镜和断层扫描。使用 JEOL 1400 透射电子显微镜观察超薄切片。dhub 蜥蜴的角膜非常薄（28-30 µm）。上皮组织构成角膜的14%，而基质构成角膜的 80%。中层基质层比前层和后层基质层明显厚。前基质中的胶原纤维（CF）直径大小不一（25-75nm）。在中后部基质中，糖胺聚糖（PG）非常大，而在前基质中则较小。进行了三维电子断层扫描，以了解 PG 和 CF 的结构和排列。后层和中层基质中大量 PG 的存在可能有助于动物保留大量水分，以防止干燥。dhub 角膜结构能够适应干燥和炎热的沙漠环境。
