Fig. 4

Measuring the spatial distribution of astrocyte processes. a Modified from Cooper et al. [11]. Center of Mass (CoM) was calculated using a series of concentric circles (red) each delineating 5% of nerve area. From the first division at the edge of the nerve to the twentieth division at the center (graph below), the CoM represents the division at which half of the glial area resides on each side. b Cross-section through a young (1.5 month) DBA/2 J optic nerve shows slight bias of astrocyte center of mass (CoM) towards edge (CoM = 7.22), low coverage (11.2%), and high parallelism (48.6%). c A 3 month DBA/2 J nerve with higher CoM (8.55) and coverage (26.7%) shows less parallelism (30.6%). d A 5 month nerve with expansive glial coverage (40.6%) shows even astrocyte distribution (CoM = 9.44) and loss of parallelism (10.3%). e CoM increases significantly with glial area (modified from [11]; r = 0.529, p < 0.001). f, g Parallelism decreases with both increasing CoM (r = − 0.55, p < 0.001) and expanding glial area (r = − 0.60, p < 0.001). Scale = 100 μm (A-C)