Brilliant cresyl blue stock solution is aimed at human medical cell diagnostics and enables differentiated hematological examination of samples of human origin.

The core principle of the solution lies in the specific staining of nucleic acids in reticulocytes (substantia granulofilamentosa), which enables morphological differentiation from erythrocytes. Here, substantia granulofilamentosa in fresh, unfixed young erythrocytes is characterized by an intense black-blue hue, which allows semiquantitative determination of reticulocytes and visualization of their morphological aspects.

Depending on the developmental state of the reticulocytes, different maturation forms of the substantia granulofilamentosa can be distinguished. Counting is performed under the microscope, with reticulocytes counted out to 1000 erythrocytes each. The result presents as a finely tuned image in which erythrocytes have a pale green staining and reticulocytes have a blackish-blue network and punctation.

This solution, which contains sodium chloride at physiological concentrations, is used in combination with anticoagulated venous blood or capillary blood, as appropriate. However, definitive diagnosis requires other accepted, valid methods.