Natt and Harrick staining solution is a special solution used in veterinary histology and cytology. It is used especially for microscopic counting of erythrocytes and leukocytes in blood samples from birds and reptiles.

The main components of this solution are sodium chloride, sodium sulfate, sodium dihydrogen phosphate monohydrate, potassium dihydrogen phosphate, methyl violet and formaldehyde. The salts serve as solvents and buffers, and methyl violet acts as a dye that specifically binds to the cell structures of erythrocytes and leukocytes, making them visible under the microscope. Formaldehyde is used as a fixative that stabilizes the structure of the blood cells during staining and subsequent microscopic examination.

The use of Natt-Herricks solution enables precise examination and quantification of erythrocytes and leukocytes in blood samples from birds and reptiles, which is of great importance for the diagnosis and treatment of various health conditions in these animals.