In fact, leukocytes can move against the flow of blood and the flow of lymph in our vessels, blood vessels and lymph vessels of our body. And that's important because leukocytes must be able to move from one location to different locations where that infection is actually taking place. Now, the way that the leukocytes actually move across the capillaries from the blood plasma to the tissue or in reverse, is via a process known as diapedesis. And what diapedesis is, it's the movement, it's the squeezing of these leukocides through the tiny slits and crevices found between the endothelial cells of our capillaries. So our capillaries consist of this tiny layer of endothelial cells and between these cells we have very tiny holes. And that's where the leukocytes actually move through via the process of diabetesis.