(a) All F4/80+ cells co-express Csf1r (anti-GFP+) in the developing kidney (n = 730 cells from 8 z-slices of a cleared E14.5 ‘MacGreen’ kidney). Inset boxes show example Csf1r+F4/80+ cells. (b) Macrophages arrange parallel to major vessels in the E15.5 kidney, but rarely contact their endothelia. (c–d) Macrophages interact with newly forming vessels in the cortical nephrogenic zone (c = E15.5 and d = E18.5). (e) Most kidney macrophages in the E17.5 nephrogenic zone are interstitial perivascular cells (n = 10 z-stacks from four kidneys). The red bar shows the percentage of interstitial macrophages that are perivascular. CM, cap mesenchyme. (f) Macrophages align with their underlying blood vessels (p for correlation <0.0001; n = 40 macrophage/blood vessel pairs from n = 8 kidneys at E17.5). (g–g’) Example of a perivascular macrophage in the nephrogenic zone, with intra-, peri-, and extra-vascular regions (g’ is a 3D rendered version of g). (h) Macrophages do not express the renal interstitial cell markers, Meis1/2. (i) Percentage of cells singly or doubly positive for CD206 and F4/80 in the E11.5 kidney and the cortical nephrogenic zone of E14.5 and E17.5 kidneys. Discernible co-staining at E11.5, 98.8 ± 0.71 [mean ±SEM], n = 5 kidneys; E14.5, 94.1 ± 1.0% of cells, n = 10; at E17.5, 96.5 ± 1.0% of cells, n = 10. (j) Representative image of CD206+F4/80+ cells (3D rendered) in nephrogenic zone. (k–k’) High-resolution 3D image of an F4/80+CD206+ macrophage. (k’) shows cellular intensity of F4/80 using colourmap developed by Nuñez et al. (2018). Scale bars: b-c = 100 µm; (d) j = 50 µm; g = 5 µm; g’) =, h, k-k’=10 µm.