Extended Data Fig. 6: Additional experiments for comparison of LN blood vessel imaging by 3PM and 2PM.
From: Intravital three-photon microscopy allows visualization over the entire depth of mouse lymph nodes
a, In vivo images of fluorescein+ blood vessels using 1,280 nm 3PE and 920 nm 2PE, and Alexa-Fluor-647+ blood vessels using 1280 nm 2PE and 1680 nm 3PE at the same site of the same LN. Three LNs from 3 mice were imaged. The number shown in each image is the average laser power (mW) under the objective lens. Scale bars, 50 μm. b, Signal-to-background ratios (SBRs) were measured at different depths. Each data point is the average and s.d. of SBRs measured in 3 blood vessels in one image. c, Normalized fluorescence signal intensity as a function of imaging depth measured in the same mouse as in a. The fluorescence signal strength at a particular depth is represented by the average value of the brightest 0.5% pixels in the XY image at that depth divided by the square (for 2PE) or cube (for 3PE) of the average power. The effective attenuation length (le) was the inverse of the slope divided by the order of the nonlinear process (that is, 2 for 2PE and 3 for 3PE).
