Abstract A morphological classification based on the cytological characteristics of peripheral blood cells of Persian horned viper (Pseudocerastes persicus persicus) from southwestern Iran is described. For this purpose, 20 blood smears for each snake were prepared immediately and air-dried. For differential leukocyte count, the blood smears of each viper were stained with a quick Romanowsky-type stain, Diff Quick. Also, 200 leukocytes were counted for each blood smear for differential relative count. The characteristic shape of the Persian horned viper erythrocytes was oval and enucleated, just like those of other ectothermic vertebrates and those of birds. Overall, five types of the leucocytes including heterophils, eosinophils, basophils, lymphocytes, and monocytes were observed in the peripheral blood smears. The results of the present study are useful for the scientists involved in snake conservation around the world and emphasize the usefulness of the microscopic studies in viper conservation.
