Fig. 1.

Imaging of the microvascular network of the chick chorioallantoic membrane (CAM). A-C Representative intravital micrographs of CAM vascular networks. A Overview. Blood flow direction is indicated for major arterial (filled arrows) and venous (open arrows) vessels. B Higher magnification of a venous vessel junction. C Close-up of a small arteriole (arrow) and capillary mesh with moving red blood cells (*) and tissue islands (**). Structures are difficult to identify from individual still micrographs, but become apparent in dynamic video recordings (see Supplemental Material 1). D-E Images of a CAM section before and after image processing. D Original image from a 20-s intravital video recording. Only the largest outflow vessel (arrow) is faintly visible. E Vessel imaging: standard deviation image (SD) showing vessel structures. High brightnessss corresponds to wide variation of light intensity over time caused by red cell movement. Black regions correspond to tissue islands. In these vessel images, the entire capillary network is visible, including tissue islands and emerging vessel structures (white arrow). F Perfusion imaging: pseudo-color image of the sum of intensity changes over time. The image shows preferential flow pathways from the lower left and lower right. In contrast, the upper right quadrant exhibits more evenly distributed flow. The vascular flow pattern corresponds to the vascular morphology in panel E