How do white blood cells effectively reach sites of infection?

White blood cells, or leukocytes, play a crucial role in the immune system by identifying and combating infections. When there is an infection, these cells are signaled to move from the bloodstream to the affected tissues.

They achieve this primarily by squeezing through the walls of blood vessels. This process, known as diapedesis, allows them to navigate through the endothelial cells that line the vessels. The ability to pass through these small gaps is essential for white blood cells to reach areas where they are needed to fight off pathogens. As they exit the bloodstream, they can then move toward the site of infection, following chemical signals released by infected or damaged tissues.

This mechanism is vital to the inflammatory response, enabling white blood cells to quickly respond to infections and initiate healing processes. The other choices do not accurately describe how white blood cells reach infection sites; for example, avoiding blood vessels would prevent them from accessing the necessary locations, and forming new blood vessels is a separate biological process unrelated to immediate immune response.