What are the two main types of leukocytes?

The two main types of leukocytes are classified as granulocytes and agranulocytes. Granulocytes include cells that have granules in their cytoplasm, which are visible under a microscope and are involved in immune responses. This category consists of neutrophils, eosinophils, and basophils. Agranulocytes, on the other hand, do not have distinctly visible granules and include lymphocytes and monocytes.

While some options might include specific types of leukocytes, they do not encompass the broader classifications. Options that specify individual leukocyte types or mix them with other blood components such as platelets and erythrocytes (red blood cells) do not accurately reflect the classification of leukocytes as a whole. Understanding these categories is vital for recognizing how different types of leukocytes function in the immune response, making the distinction between granulocytes and agranulocytes a foundational concept in immunology and laboratory animal research.