Fixed confocal images of CIC structures. Images are acquired with Leica TCS SP8 FSU laser scanning confocal microscope using a 40× oil lens. CLL cells cytoplasm are labeled in green and the BMF cytoplasm in red. (A) Vacuole-like holes are present in the cytoplasm of BMF (a), where they are occupied by CLL cells (b). Comparison white to white and yellow to yellow arrows in panel Aa-b. Bar = 30 um. (B) Two-dimensional (2D) images with green tumor cells, red BMF, and the nuclei of BMF and CLL are in blue (a); 3D images reconstructed using Imaris v10.0.; BMF cells are visualized as the red surfaces and CLL cells as the green surfaces (b); red surfaces are transformed to a transparent state (c); the entry process (d-f). (C) Time-lapsed microscopy showing CLL cells are internalized, remain viable, and move within the BMF. BMF are visualized as either red or transparent pink and CLL cells as the green surfaces (scale bar, 20 μm); track cell 1, 2, and 3 through (a-c); and compare solid images (a-c) with the corresponding transparent images (d-f).