White Blood Cells (WBCs)

Lesson 10 of 16 · Detailed theory + identification points

HistologyBlood / Haematology5 ID Points

Points of Identification

5 points

1Neutrophils: multilobed nucleus, fine pink granules – most common

2Eosinophils: bilobed nucleus, coarse red-orange granules

3Basophils: large purple-black granules often obscuring nucleus

4Lymphocytes: round dense nucleus, scant blue cytoplasm

5Monocytes: kidney-shaped nucleus, abundant grey-blue cytoplasm

Detailed Theory

Object: Examination of White Blood Cells (Leukocytes)

General Overview

Leukocytes are nucleated cells essential for immunity. They are classified into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes, monocytes). On a Romanowsky-stained smear (Wright/Giemsa), each type has distinctive nuclear morphology and cytoplasmic granules.

Blood smear overview — Peripheral blood smear: neutrophils (multilobed), lymphocytes (dark round nuclei), and a monocyte (indented nucleus) are visible.

WBC types high magnification — High magnification: neutrophil (multilobed), eosinophil (red granules), basophil (purple granules).

Granulocytes

Feature	Neutrophil	Eosinophil	Basophil
Nucleus	2–5 lobes	Bilobed	Bilobed / S‑shaped
Granules	Fine, pink-purple	Coarse, red‑orange	Large, purple‑black
Size (µm)	10–12	12–15	10–14
% in blood	40–70%	1–5%	<1%
Main function	Bacterial phagocytosis	Anti‑parasitic, allergy	Hypersensitivity

Agranulocytes

Feature	Lymphocyte	Monocyte
Nucleus	Round, dense chromatin	Kidney‑shaped / indented
Cytoplasm	Scant, pale blue rim	Abundant, grey‑blue
Size (µm)	6–15	12–20
% in blood	20–40%	2–8%
Main function	Adaptive immunity	Macrophage/dendritic precursor

Distinguishing Features on Smear

Neutrophils – multilobed, most numerous
Eosinophils – bright red granules, bilobed
Basophils – dark purple granules, often obscure nucleus
Lymphocytes – round dark nucleus, thin cytoplasm
Monocytes – large, indented nucleus, abundant grey cytoplasm

Video Lesson

White Blood Cells (WBCs) — Histology Video Lesson

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References

4 sources

1
Ross MH, Pawlina W. Histology: A Text and Atlas (8th ed.). Wolters Kluwer; 2020.
2
Young B, O'Dowd G, Woodford P. Wheater's Functional Histology (6th ed.). Churchill Livingstone/Elsevier; 2014.
3
Hoffbrand AV, Moss PAH. Essential Haematology (7th ed.). Wiley-Blackwell; 2016.
4
Bain BJ. Blood Cells: A Practical Guide (5th ed.). Wiley-Blackwell; 2015.

Disclaimer: These notes are for educational purposes only and compiled from standard histology textbooks. Clinical interpretation of slides requires a qualified histologist or pathologist.

Red Blood Cells

Simple Epithelium

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