Which granulocyte contains cytoplasmic granules that stain reddish-orange and participates in allergic responses and parasitic infections?

Which granulocyte contains cytoplasmic granules that stain reddish-orange and participates in allergic responses and parasitic infections?

• A. Lipid Droplet
• B. Eosinophil
• C. Megakaryocyte
• D. Platelets

Answer: (B)

Eosinophils are the granulocytes with cytoplasmic granules that stain reddish-orange when viewed with standard eosin staining. Those bright granules come from proteins in the granules that bind the eosin dye, giving that distinctive color. Eosinophils are especially involved in allergic responses and in defense against parasites, such as helminths, by releasing toxic granule proteins and regulating other parts of the inflammatory response. The other options aren’t granulocytes and don’t have the reddish-orange cytoplasmic granules: lipid droplets are storage components inside various cells, megakaryocytes produce platelets, and platelets are small cell fragments with a different granule makeup and are not the classic reddish-orange–staining granulocytes involved in allergy and parasitic defense.

Eosinophils are the granulocytes with cytoplasmic granules that stain reddish-orange when viewed with standard eosin staining. Those bright granules come from proteins in the granules that bind the eosin dye, giving that distinctive color. Eosinophils are especially involved in allergic responses and in defense against parasites, such as helminths, by releasing toxic granule proteins and regulating other parts of the inflammatory response. The other options aren’t granulocytes and don’t have the reddish-orange cytoplasmic granules: lipid droplets are storage components inside various cells, megakaryocytes produce platelets, and platelets are small cell fragments with a different granule makeup and are not the classic reddish-orange–staining granulocytes involved in allergy and parasitic defense.