Figure 1.

(A) Micrograph taken at the microscope eyepiece using an iPhone 3. The dotted scale bar shows the diameter of a maximally dilated arcade arteriole at that location (21.3 μm) and of a maximally dilated terminal arteriole (8.7 μm). The black and white inset is digitized from the video image showing the micropipette containing FITC-dextran, and the exposure ‘cloud’ that saturates both arterioles with one exposure. Diameters were measured at the regions exposed to micropipette contents. (B) Micrograph taken with a Retiga color camera to illustrate the tissue following thermal stress. The heat rim is readily apparent following 20s exposure to 50 °C; no rim is seen if the Pt wire is gently laid on the overlying connective tissue without heat. The white circle outlined the approximate dimensions of 500 um from the heat rim; data was taken within 1000 um of the heat rim. The estimated temperature gradient is given in the Discussion.