Fig. 2

In vivo imaging of monocyte infiltration through retinal vasculature during early neurodegeneration. In vivo retinal images of Arr1^−/− CCR2^+/rfp mice before and during photoreceptor degeneration. The fluorescence images (SLO) showed only fleeting RFP⁺ signal prior to degeneration (a), but in the same vessel 24 h later, RFP⁺ cells studded the interior (b) and could also be seen in other large caliber vessels and within the parenchyma of the central retinal (b′). By 48 h, RFP⁺ cells had escaped the vasculature and appeared throughout the retina (c, c′). The bright field (reflectance) images taken concurrently with the fluorescence (SLO) show the position of the blood vessel in the same animal over time. SLO images are frames from Additional file 2: Video 0 h; Additional file 3: Video 24 h; Additional file 5: Video 48 h. (d) Color-coded representation of Additional file 4: Video ext 24 h (different Arr1^−/− CCR2^+/rfp animal, 24 h), where each pixel was colorized based on the time epoch of the video in which RFP⁺ cells appeared. The largest diameter vessel is largely white because the corresponding pixels were RFP⁺ throughout the entire session due to persistent RFP⁺ cell adherence to the vessel walls. Notice transient epochs of cell adherence to finer capillaries as revealed by streaks of blue, green, red, etc. The grayscale projection of maximal pixel intensities over time (right) outlines the vascular network in greater detail. Scale bars are 100 μm in a, b, c, d, and 500 μm in b′, c′