Adhesion molecule expression and the infiltration of leukocytes. Adhesion molecule expression and the infiltration of leukocytes subset in the wound shown at 2 different stages in wound healing as determined using immunohistochemistry. (A) β₁-Integrins are highly up-regulated 5 and 8 days after wounding (arrows; original magnification, × 100). (B) ICAM-1 expression is clearly up-regulated within the wounded tissue at day 3 compared with day 0 (arrow; original magnifications, × 100 and × 250, respectively). (C) Massive infiltrates of macrophages are present 1 and 3 days after wounding. Arrows indicate examples of positive staining (original magnification, × 250).