Figure 4. Monocyte transmigration across the BBB.

Monocyte transmigration is a multistep process, (A) consisting of capture and rolling, chemokine-mediated activation of the monocyte and subsequent firm arrest, intravascular crawling with the formation of focal adhesions to the vasculature, and ultimately, diapedesis. (B) An enlarged image illustrating some of the homotypic monocyte–EC interactions, which mediate diapedesis.