Paul Ehrlich contributed to hematology by developing a classification system for white blood cells based on what characteristic?

• A. Morphology
• B. Size
• C. Nuclear position
• D. Cytoplasmic inclusions

Answer: (A)

White blood cell classification by Ehrlich was based on how the cells look under stained microscopy. His differential staining illuminated distinct cellular features—like the presence and type of cytoplasmic granules and the shape and segmentation of the nucleus—that allowed grouping into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes). This focus on visible structure and staining pattern is what the classification hinges on, i.e., morphology. Size alone isn’t the defining factor, and while nuclear position or cytoplasmic inclusions can be parts of the overall look, they don’t capture the full basis of Ehrlich’s system.