Immunolocalization of intermediate filaments in the kidney of the dromedary camel (Camelus dromedarius)

Abstract

Intermediate filaments belong to a large family of proteins which contribute to the formation of the cytoskeleton. The immunolocalization of cytoskeletal proteins has been used extensively in the diagnosis of various renal pathologies. The present study described the immunolocalization of the cytoskeletal proteins vimentin, desmin, smooth muscle actin, and cytokeratin 19 in the normal kidney of the dromedary camel. Kidney samples from eight adult camels were processed for histology and immunohistochemistry. The kidney was enclosed in a renal capsule composed of vimentin immunoreactive fibroblasts and smooth muscle actin immunoreactive smooth muscle cells. The smooth muscle cells in the renal capsule did not exhibit desmin immunoreactivity. Podocytes forming the visceral layer of the glomerular capsule were immunoreactive for vimentin. Immunoreactivity for vimentin and smooth muscle actin in the parietal layer of the glomerular capsule varied, with both reactive and non-reactive cells observed. Intraglomerular mesangial cells were immunoreactive for smooth muscle actin and desmin, but non-reactive to vimentin. The endothelial lining of blood vessels was vimentin immunoreactive, while smooth muscle actin and desmin were demonstrated in the smooth muscle cells of the vessels. The thin limbs of the loops of Henle in cortical nephrons displayed vimentin immunoreactivity. The proximal and distal convoluted tubules, as well as the collecting ducts were negative to vimentin, smooth muscle actin, desmin and cytokeratin 19 immunostaining. In conclusion, the present study has revealed that similarities and differences exist in the immunolocalization of cytoskeletal proteins in the camel when compared to other mammals. The presence of smooth muscle actin in the parietal cells of the glomerular capsule suggests a contractile function of these cells. The results of the study indicate that vimentin and smooth muscle actin can be used as markers for the identification of podocytes and intraglomerular mesangial cells, respectively, in the camel kidney.