VEGF-R2 expression in neonatal and thymus. (A) Immunofluorescent staining of sections of neonatal (top row) and adult (bottom row) thymus with VEGF-R2 (leftmost panel) and CD31 (2nd from left) as described in “Methods.” The merged images (2nd from right) show overlap between VEGF-R2 and CD31 represented by yellow areas. The rightmost panels represent the merged images with DAPI included. (B) Quantitation of VEGF-R2 expression by immunofluorescence in neonatal and adult thymus. *P < .001. (C) Percentage of VEGF-R2⁺ cells in each subset (endothelial cells: CD45-CD31⁺; TECs: CD45⁻MHCII⁺; hematopoietic cells: CD45⁺) of neonatal and adult thymus measured by FACS analysis. Error bars represent standard deviation.