Figure 2. Region specific reduction of vascular length and branching density and increased vascular radii.

(A) The averaged vasculature length density of 2-month-old (N=4) and 18-month-old (N=5) brains registered to the Allen CCF. (B-C) Summed vessel length (B) and brain volume (C) in 2-month-old and 18-month-old brains. (D-F) Scatter plots of averaged vascular length density (m/mm³) (D), vascular branching density (1/mm³) (F), and vascular radii (μm) between 2-month-old (x axis) and 18-month-old (y axis) brains across different brain regions. Areas with statistically significant differences were highlighted with magenta boxes. (G-I) Scatter plots of the isocortex data for averaged vascular length density (G), vascular branching density (H), vascular radii (I) between 2-month-old (x axis) and 18-month-old (y axis) brains. Isocortical areas are color coded based on grouping in J. The solid yellow line represents y=x and the dotted line on either side represents a 10% difference from the solid yellow line. (J) Isocortical flatmap with Allen CCF border lines and region-based color-coding. Y axis: Bregma anterior-posterior (A-P) coordinates, X axis: the azimuth coordinate represents the physical distance by tracing the cortical surface on the coronal cut. (K) Averaged vascular length density of different cortical layers in the flatmap between 2-month-old and 18-month-old brains. A white arrow highlights the significant decrease of vascular length density in the layer 6 cortical layers. (L-M) 250μm maximum intensity projection images of the primary somatosensory cortex (L) and the infralimbic cortex (M) with vascular tracing (green on the right side) between 2-month-old and 18-month-old brains. Note the significant reduction of vasculature in the deep layer. (N) Both vascular length and branching density showed significant reductions in layer 6. Brain region abbreviations can be found in Supplementary data 1 or Allen atlas at https://atlas.brain-map.org/atlas?atlas=602630314.