Introduction: Blood Cells
Blood contains several different types of cells. Some cells, such as red blood cells, carry oxygen to other cells. Other types of cells, such as white blood cells or leukocytes, provide protection from foreign cells and infectious agents. Cell fragments called platelets provide protection against bleeding. The red blood cells of different animals can have different structures.

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Human macrophage - phagocytosis
Human white blood cells called macrophage engulf foreign particles in a process called phagocytosis. The cell to the left of center is shown phagocytosing one of many yeast particles flowing by.

Elapsed time 2.5 minutes.
Activated human macrophage isolated from whole human blood (generously provided by UC San Francisco) were plated in chambered coverslips with opsonized yeast particles. Images were taken on an inverted compound microscope at 37°C, 7% CO2 with a 40x phase contrast objective and digital camera.