Which structural feature characterizes eosinophils?

Which structural feature characterizes eosinophils?

• A. Bi-lobed nuclei
• B. Large, coarse eosinophilic granules
• C. Nucleus not obviously multi-lobed
• D. Bi-nodal with small granules

Answer: (A)

Eosinophils stand out mainly because of their nucleus. On a stained smear, you’ll see a nucleus with two lobes connected by a thin strand—what we call a bilobed nucleus. This two-part shape is a reliable clue that helps distinguish eosinophils from other white blood cells, especially neutrophils, which tend to have many lobes, and basophils, where the nucleus is often obscured by large granules. The eosinophil’s granules are indeed large and stain brightly with eosin, but the bilobed nucleus is the most distinctive, defining feature. So the statement describing a bilobed nucleus best matches what characterizes eosinophils. The other descriptions either misstate the nucleus shape or describe granule size in a way that doesn’t align with the typical eosinophil appearance.

Eosinophils stand out mainly because of their nucleus. On a stained smear, you’ll see a nucleus with two lobes connected by a thin strand—what we call a bilobed nucleus. This two-part shape is a reliable clue that helps distinguish eosinophils from other white blood cells, especially neutrophils, which tend to have many lobes, and basophils, where the nucleus is often obscured by large granules. The eosinophil’s granules are indeed large and stain brightly with eosin, but the bilobed nucleus is the most distinctive, defining feature. So the statement describing a bilobed nucleus best matches what characterizes eosinophils. The other descriptions either misstate the nucleus shape or describe granule size in a way that doesn’t align with the typical eosinophil appearance.