Different types of white blood cells are classified histologically, they are distinguished from one another based on their morphology and their

• A. Cell size
• B. Number in a sample
• C. Staining characteristics
• D. Ability to engulf bacteria

Answer: (D)

White blood cells are told apart in tissue samples mainly by how they look under the microscope and how they take up stain. The shape and structure of the nucleus and cytoplasm (morphology) combined with staining patterns reveal each cell type. Staining characteristics are especially useful because different cells contain different granules and chromatin that stain in distinct ways, making features like nuclear lobes and granule color easy to see with common stains. For example, neutrophils have a multi-lobed nucleus and pale cytoplasm, eosinophils show red-orange granules, basophils have dark granules, lymphocytes are small with a dense nucleus, and monocytes are larger with a kidney-shaped nucleus. The ability to engulf bacteria is a functional property of some of these cells, not a histological feature used to identify them.