are they white? It is because of the white blood cells (see the
photo of a white blood cell on the right). If you smeared the pustule
on a glass slide, stained the slide, and looked at it under a microscope
you would actually be able to see the white blood cells! The white blood
cells are attracted to
under your skin. Why?
Remember the description of a splinter from the introduction to the
unit? The splinter and the bacteria on it crossed the first line of defense,
the skin. The second line of defense is the
white blood cells.
cells are attracted to wounds or areas where bacteria has injured the
skin. The white blood cells become concentrated in an area, as they block
bacteria from entering surrounding tissues. Your first and second lines of defense,
the skin and immune system, work together to keep your body healthy and
free from infection.