Movie S4.

PC/PB actively migrate in the outer T zone and thereby show transient interactions with multiple FRC. LN slice from an immunized (SRBC, d6) pCol-GFP mouse was stained with anti-CD138 antibodies (red) and imaged during 20 min with a confocal microscope. The trajectory of the CD138-positive cells is represented in white. Frame intervals, 20 sec. The animation represents a single optical section of 10 μm taken 20 μm below the cut surface of the slice.