A dendritic cell (arrow) as it moves through a sea of lymphocytes. The dendritic cell continually extends processes in different directions, probing the environment. The lymphocytes are either round or hand-mirror in shape. During this sequence, the dendritic cell does not form any stable contacts with the lymphocytes. Such contacts form when lymphocytes recognize antigen on the dendritic cells.

One view of dendritic cells from mouse spleen, where the cells were originally discovered. The cells are continually sending out small processes. Within the cell, the nucleus pulses back and forth. The cytoplasm has many mitochondria.

Another view of dendritic cells from mouse spleen, where the cells were originally discovered. The cells are continually sending out small processes. Within the cell, the nucleus pulses back and forth. The cytoplasm has many mitochondria.

A dendritic cell next to a macrophage. The dendritic cell makes and retracts processes, and the nucleus moves back and forth. The cytoplasm has many mitochondria. The macrophage nucleus is sessile, and the cytoplasm has many granular lysosomes of varying size.