This video provides a detailed microscopic guide to identifying and differentiating the five types of leukocytes (white blood cells) on a Wright-stained peripheral blood smear, viewed under 1000x oil immersion magnification. The speaker details the key morphological features of neutrophils, lymphocytes, monocytes, eosinophils, and basophils, focusing on nucleus shape, cytoplasm color, and the specific characteristics of their granules. The discussion also covers red blood cell morphology, explaining their biconcave shape and central pallor, as well as the appearance of platelets. Comparisons are made to distinguish similar-looking cells, such as monocytes and band neutrophils, and the differences between blood smears and tissue sections are briefly addressed.
A Microscopic Guide to Blood Cell Identification
0:07 Neutrophils: These are the most common white blood cells in adults. They are identified by their segmented nucleus (typically 3-5 lobes) and fine, "baby girl pink" cytoplasmic granules. A neutrophil with more than five segments is "hypersegmented," while one with less than three is "hyposegmented."
1:55 Lymphocytes: These are the second most common white blood cells in adults but the most common in newborns. A mature lymphocyte has a large, round nucleus approximately the size of a red blood cell, with a very thin rim of blue cytoplasm.
2:23 Monocytes: These large cells have abundant blue-gray cytoplasm, a variably shaped (often kidney bean or band-shaped) nucleus, and may contain vacuoles. The presence of vacuoles is a helpful feature in distinguishing them from reactive lymphocytes or band neutrophils.
2:38 Differentiating Monocytes and Band Neutrophils: A "band" is an immature neutrophil with a smooth, non-segmented nucleus. An increase in bands ("bandemia") indicates a "left shift." Because its nucleus can look similar to a monocyte's, the key differentiator is the cytoplasm: neutrophils have pink granules, while monocytes have blue-gray cytoplasm and potential vacuoles.
4:09 Eosinophils: Easily identified by their large, chunky, "hot pink" or "Barbie pink" granules. These granules are larger and more refractile (shiny) than the fine granules of neutrophils.
5:22 Basophils: The rarest white blood cell in circulation. They contain large, coarse, dark purple granules that often obscure their bilobed nucleus. They degranulate very easily, making them morphologically variable. The video also briefly discusses their debated relationship to mast cells, noting that mast cells typically have a central, round nucleus.
7:37 Red Blood Cells: On a smear, these appear as biconcave discs, creating a distinctive central pallor that looks like a donut hole. This clear area should ideally make up about one-third of the cell's diameter.
8:41 Platelets: These are small, granular, purple cell fragments that originate from megakaryocytes. They can be seen individually or in small aggregates on the blood smear.