Impaired PMN adhesion and extravasation in the absence of Syk. Number of adherent leukocytes per square millimeter of venular surface area (top panel, intravascular) and perivascular leukocyte accumulation (bottom panel, perivascular) after 15 minutes of fMLP superfusion of the cremaster muscle using Syk^+/– and Syk^–/– bone marrow chimeric mice. Data shown represent intravascular and perivascular PMNs and mononuclear (Mono) cell counts in whole-mount preparation of the cremaster muscle. n = 4 (Syk^+/– animals); n = 4 (Syk^–/– animals). Means ± SEM are shown. n.s. indicates not significant; *P < .05.