Hematology Lab: Granulocytic Series

Granulocytic Series

• Stages: myeloblast, promyelocyte, myelocyte, metamyelocyte, band, and mature granulocyte (ben)
• Myeloblast: • 15-20 um in diameter • N:C ratio 4:1 • Cytoplasm: moderate blue, no granules • Nucleus: round to oval, extremely fine chromatin, reddish purple, 2-5 nucleoli • First stage, found in bone marrow
• Promyelocyte: • 15-21 um in diameter • Cytoplasm: presence of primary (azurophilic) granules, blue to reddish purple • N:C ratio: 3:1 to 2:1
• Myelocyte: • 12-18 um in diameter • Secondary granules (specific granules) begin to appear • Last stage capable of mitosis
• Neutrophilic myelocyte: • pink specific granules
• Eosinophilic myelocyte: • dirty orange to red granules
• Basophilic myelocyte: • dark blue-purple specific granules

Band

• 9-15 um in diameter
• Sausage shape, narrow, horse shoe-shaped nucleus
• Indentation in nucleus is 1/3 the diameter of the cell
• Last stage found in bone marrow, first stage found in circulation (0-3% in circulation)

Monocytic Series

• Stages: monoblast, promonocyte, and monocyte
• Monoblast: • 12-20 um in diameter • Found in bone marrow, mature neutrophil • Cytoplasm: moderately basophilic or blue-gray • N:C ratio 4:1 • Nucleus: round or ovoid, light blue-purple, lacy chromatin, 1-2 nucleoli
• Promonocyte: • 14-18 um in diameter • Cytoplasm: ground glass appearance • May contain dust-like azurophilic granules • Nucleus: oval, may have a single fold or fissure, 1 nucleoli
• Monocyte: • 14-20 um in diameter • Cytoplasm: abundant, blue-gray, ground glass appearance due to many fine azurophilic granules • Irregular, presence of pseudopods • Nucleus: kidney-shaped, brain-like convolution, lacy chromatin, no nucleoli present

Eosinophil

• 10-16 um in diameter
• Dark purple to blue-black granules obscuring the nucleus
• Nucleus: bilobed or rarely 3-4 lobes

Lymphocytic Series

• Lymphoblast: • 10-18 um in diameter • Cytoplasm: no granules, more abundant than myeloblast, moderate to dark blue • Nucleus: round to oval, contain 1-2 distinct nucleoli • N:C ratio: 4:1
• Prolymphocyte: • Smaller than lymphoblast • Cytoplasm: moderate to dark blue, may contain occasional azurophilic granules • Round, ova or slightly indented, chromatin pattern is clumped, 1-2 nucleoli
• Lymphocyte: • 8-10 um in diameter • Cytoplasm: light blue, scanty to moderate, with few azurophilic granules • Nucleus: purple, dense, clumped chromatin, round, eccentric, no nucleoli

Megakaryocytic Series

• Stages: megakaryoblast, promegakaryocyte, granular megakaryocyte, mature megakaryocyte, and platelet
• Megakaryoblast: • 20-50 um in diameter • Cytoplasm: non-granular, blue, darker than myeloblast, with small, blunt pseudopods • Nucleus: round, oval, multiple nucleoli • N:C ratio: 10:1
• Promegakaryocyte: • 20-60 um in diameter • Cytoplasm: more abundant, less basophilic, granules begin to form • Nucleus: multiple nucleoli are visible, irregular in shape, may show lobulation • N:C ratio: 4:1 to 7:1

WBC Count

• Refers to the routine procedure that gives an approximation of the total number of leukocytes in the circulation
• Function of the WBC is to provide immunity, the ability to resist infection
• In a normal adult, WBC ranges from 4,000-11,000/mm3
• A count above normal is called leukocytosis, while a count below normal is called leukopenia

Direct Eosinophil Counting

• Eosinophil: a granulocyte present at sites of allergic reaction and parasitic infection
• Can be obtained indirectly by determining WBC count multiplied by the eosinophil differential
• Normal range: 50-350 x 10^6/L or 0.5-3.5% of WBC
• Eosinophilia: increased eosinophils above normal, causes include allergic reactions, parasitic infestation/infection, brucellosis, and certain leukemias
• Eosinopenia: decreased eosinophils count, causes include hyperadrenalism, shock, and ACTH administration