Cover picture: Both figures depict blood flow in mice in real time and, thus, demonstrate the speed of the multibeam fluorescence two-photon laser scanning microscope presented in our work. Dual-color images were detected simultaneously with two independent CCD cameras based on color splitting by a 570-nm cut-off dichroic mirror. (Left) A time projection over 11 two-dimensional fluorescence images of a blood vessel and surrounding tissue stained by intravenous injection of Rhodamine-6G. The time delay between two consecutive numbers was 50 ms. Shown is a cell-doublet rolling on the surface of the vessel (open outlines). (Right) A time projection over 11 dual-color, two-dimensional fluorescence images of a blood vessel (open outlines) stained with Rhodamine 6G (yellow). Spleen cells previously stained either with CFSE (green) or CTO (red) and additionally injected into the mouse are represented green and red, respectively, because they were detected by only one of the two CCD cameras. The green numbers indicate the position of a CFSE-stained cell at six different time points, whereas the red numbers indicate the position of a CTO-stained cell at five succeeding time points. The time delay between two consecutive numbers is also 50 ms. See the article by Niesner et al. on page 2519.