Light and Transmission Electron Microscopic Analysis of Seasonal Renal Adaptations in the Dromedary Camel: Morphometry and Immunolocalization of β-Catenin, iNOS, and Aquaporin-4.

The dromedary camel (Camelus dromedarius) exhibits remarkable renal adaptations that enable survival under extreme desert conditions; however, seasonal ultrastructural and molecular variations in the kidney remain insufficiently characterized. This study investigated the histological, ultrastructural, morphometric, and immunohistochemical alterations in the camel kidney during spring and summer using light microscopy, transmission electron microscopy (TEM), and quantitative image analysis. Microscopically, the renal cortex displayed well-defined renal corpuscles and convoluted tubules, while the medulla exhibited elongated loops of Henle and collecting ducts. Morphometric analysis revealed significant increases in renal corpuscle diameter (177.7 ± 7.5 µm), Bowman's space width (20.23 ± 1.2 µm), and proximal (31.97 ± 1.9 µm) and distal (20.76 ± 0.98) tubular epithelial height during summer. Ultrastructural examination demonstrated seasonal modulation of mitochondrial density, basal infoldings, and intercellular junctional complexes in tubular epithelial cells. Immunohistochemically, strong β-catenin expression was observed in the cytoplasm and cell membranes of proximal and distal tubules during spring, whereas summer samples showed reduced reactivity. In contrast, inducible nitric oxide synthase (iNOS) and aquaporin-4 (AQP-4) exhibited enhanced expression during summer, particularly in collecting ducts, suggesting intensified water reabsorption and nitric oxide-mediated regulatory activity under heat stress. These findings demonstrate coordinated season-associated remodeling of renal microarchitecture and protein expression, providing microscopic evidence for adaptive mechanisms that optimize water conservation in camels. The study highlights the value of integrated ultrastructural and immunolocalization approaches in understanding functional renal adaptation to environmental stress.