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 white blood cells
As part of our immune system, white blood cells such as these move toward sites of infection.

Elapsed time, 20 minutes.
A drop of blood was placed on a coverslip with a silicon spacer and diluted with saline solution. The drop was incubated at 37°C for 20 minutes, then red blood cells were washed away. A mixture of saline solution with human serum was used to cover the remaining cells. Images were taken on an upright inverted microscope with a 40x DIC objective at room temperature using a digital camera.