Extended Data Fig. 2: Label-free in vivo visualization of capillary blood flow via third harmonic effect generated by red blood cells.
From: Niche-specific dermal macrophage loss promotes skin capillary ageing
a-b, Simultaneous visualization of blood flow through the superficial capillary plexus via third harmonic generation (white) from red blood cells (RBC) and intravenous rhodamine dextran (RhDex) (red). c, Quantifications of RBC and RhDex labelling of the upper dermal superficial capillary plexus (n = 3 mice in total; four 500 µm2 regions per mouse; Capillary labelling was compared by one-way RM ANOVA and Tukey multiple comparison tests; mean ± SD). d, Scheme of red blood cell (RBC) flow through a segment of the superficial skin capillary network. During three-dimensional image acquisition, flowing red blood cells are captured at different x,y positions for each z-section along the capillary segment. Pseudo colouring each z-step through a capillary segment distinguishes flowing RBCs as a multicolour patchwork or rainbow-effect and leaves obstructed/non-flowing RBCs as white (full overlap of all colours). e, Representative image of RBC visualization in the upper dermis in Csf1r-EGFP; R26-mTmG mice. f, Representative optical z-sections through upper dermal capillaries. Third harmonic signal is pseudo coloured differently for each z-step to visualize RBC movement along the capillary segments during image acquisition. Scale 50 µm.
