Figure 1.

Wide variation in collateral number and diameter among Collaborative Cross strains. (a) Collaterals between the right and left MCA and ACA trees of 3 strains (stars; representative collateral shown in lower panels; bars = 1 mm in upper figures, 40 µm in lower figures). (b) Strain names and number of animals per strain given below each bar ( $\ddot{\text{x}}$  = 7.9 ± 0.2 per strain; 537 mice total). Strain CC044 has the largest number, CC031 the largest diameter, and CC036 the smallest number and diameter. CC049, CC055, CC053, CC036 were used in F2 crosses (Figure 4), CC036, CC032, CC016 in AAV9-expression assays (Figure 6). CC039 has number and diameter similar to B6 mice. Among the 60 CC strains: fold ranges and heritability values are given, distribution of collateral number is shown (c), and diameter correlates with number (r² = 0.23, p < 0.001, Supplemental figure I). Values are mean ± SD for this and subsequent figures.