In 1949, Dr. George Brecher developed a stain called new methylene blue to identify immature erythrocytes (reticulocytes) based upon aggregations of RNA within disintegrating ribosomes. This RNA is at its highest level immediately after enucleation of the cell and continues to decrease until its complete absence in the fully mature erythrocyte. Reticulocytes are so named due to their mesh-like (reticular) network of ribosomal RNA which, after staining, is readily visible with a blue granulofilamentous appearance. The quantitative evaluation of reticulocytes in peripheral blood is an important test used in the assessment of erythropoiesis, bone marrow function, and anemia typing.
A single chemical agent, dye or solution intended for the artificial colouration of specific target tissue structures, intra/extracellular elements and/or infectious microorganisms, in a clinical specimen, for their subsequent visualization, examination, identification and/or differentiation.