Final answer:
Macrophages and dendritic cells are agranulocytes involved in the immune system. Macrophages are phagocytes with variable lifespans, while dendritic cells are key in antigen presentation.
Step-by-step explanation:
Macrophages and dendritic cells (DCs) are types of white blood cells that are essential for the immune system. Macrophages are agranulocytes derived from monocytes and are known for their ability to phagocytize debris, foreign pathogens, and dead cells. Their lifespan can vary, with some occupying fixed locations in tissues and others freely circulating. Dendritic cells, which also develop from monocytes, are primarily found in tissues exposed to the external environment such as skin and mucous membranes. They excel in presenting antigens to initiate an adaptive immune response. Both cell types are integral in coordinating both innate and adaptive immunity and have a longer lifespan compared to the granulocyte counterparts, which usually live for only hours to days.