Figure 1: In vivo side-view endomicroscopy.

(a) Schematic of a laser-scanning side-view endoscope. The raster-scanned beam in x and y dimensions is relayed by grade-index lenses in the probe and directed by a 90° prism to a side-view window. ζ and φ represent the axial and circumferential coordinates, respectively, in the imaging plane. θ denotes the rotation angle of the probe, or the angle between x and φ axes. (b) Coordinate transform between the proximal (x-y) and distal (ζ-φ) imaging planes. The trace of the raster-scanned beam is depicted in blue solid lines. (c) In the imaging setup, the laser beam emitted from the endoscope is projected to a stage. Dashed lines depict the outline of the beam diverging after going through the imaging plane. Inset, distal tip of the probe. (d) Three-dimensional rendered fluorescence image of the vasculature in the descending colon of a normal C57B6/L mouse. (e) A fly-through rendered image of d. The wall-to-wall diameter is 1.3 mm. (f–h) Fluorescence images of the microvasculature in the esophagus (f), vasculature of villi in the small intestine (g) and MHC-II–GFP expression in dendritic cells in the trachea (h). Blood vessels were visualized by intravenously injected FITC-dextran conjugates. In f–h, the horizontal axis represents the circumferential angle φ. Scale bars, 200 μm.