Figure 1. Steady-state trans-epithelial delivery of luminal material in the mouse small intestine.

Intestines from CD11c^YFP reporter mice injected intraluminally with 10kD dextran (red) imaged with intravital 2P microscopy from the (a) serosal or (b) luminal surfaces. Optical sections at increasing depths (shown in μm) revealed dextran in the lumen (asterisks), the crypts (yellow arrows), on the epithelial surface (unfilled arrow) and columns of dextran that traversed the epithelium (white arrows). Dextran was generally excluded from the LP as identified by CD11c^YFP+ LP-DCs (green) below the DAPI stained epithelial nuclei (blue in b). Scale bars = 100μm. (c) Time-lapse recording of LP-DC (green) making repeated contacts with a dextran column (red, white arrow) crossing the epithelium (DAPI stained nuclei, blue). Scale bar=50μm, time stamp=min:sec elapsed time from the start of imaging. (d) Rendered confocal image of a CD11c-YFP⁺ DC (green) in contact with a dextran filled epithelial cell (red). Panels show orthogonal views; contact is indicated by the white arrow. Scale bar = 5μm. (e) Confocal image of a dextran containing cell (red) bordered by a continuous e-cadherin (blue) positive surface (white arrow). Asterisk indicates the position of an optical section near the cell's center showing intracellular dextran. A CD11c^YFP+ DC (green, yellow arrow) positioned near the base of the epithelium. Orthogonal projection (bottom panels); red channel removed (right panels). Scale bar= 5 μm.