Fig. 3: Reduced vascular density and simplified PCV tributary structure in aged mice.
a, Reconstruction of adult layer 4 PCV branch network with (left) and without (right) pre-convergence capillaries. b, Pie charts showing percentage of total vascular segments (left) and total vascular length (right) represented by pre-convergence capillaries and other tributary vessels in all PCV tributaries across layers and age. c, Age-related change in percentage of pre-convergence capillary segments (**P = 0.008) and length in PCV tributaries (**P = 0.005). d, Reconstruction of adult layer 6/CC PCV tributary with example ROI for vascular length density measurements. The inset shows raw data and segmented vessels in an ROI. e, Vascular length density across layers in adult and aged mice: layer 6/CC, ***P < 0.001. f, Average number of vascular segments in tributaries of adult and aged mice across layers: *P = 0.016. g, Hypothetical model for change in tributary complexity of aged mice involving pre-convergence capillary regression (also see Supplementary Fig. 4). h, Measurement of structural properties of individual pre-convergence capillaries. i, Length of individual pre-convergence capillaries: layer 2/3, ***P < 0.001; layer 6/CC, **P = 0.007. j, Tortuosity of pre-convergence capillaries: layer 6/CC, ***P < 0.001. k, Example of a stalled blood flow in pre-convergence capillary observed in vivo (encircled by the dotted red line). The plugging cell is marked with a white arrow. l, Pie chart showing vessel types experiencing stalled flow across all layers and both ages, as a percentage. m, Examples of pre-convergence capillaries in adult mice exhibiting very low (yellow dotted lines) or stalled (red dotted lines) blood flow (upper row images) that regressed over time (bottom row images). For graphs in panels e, f, i and j, the adult group includes n = 12 mice for layers 2/3 and 4 and n = 11 mice for layer 6/CC, and the aged group includes n = 11 mice for all layers. The data are shown as mean ± s.e.m. and are analyzed by two-way ANOVA with Holm–Šídák’s post hoc comparison testing (see Supplementary Table 1 for details on statistics). E, Euclidean distance; L, length; T, tortuosity.
