Models of Purkinje cell dendritic tree selection during early cerebellar development
Fig 2
Granule cell migration model as an environment for Purkinje cell growth.
(A) A representative simulation cube at the end of the simulation visualized from X side. Red large spheres are Purkinje cell somas. Blue small spheres with processes growing upward are Bergmann glia. Numerous green thin threads are axons of granule cells in the main simulation volume (where Purkinje cell somata and Bergmann glia are present, see panel E), and orange fibers are ingrowing parallel fibers. (B) Schematic representations of how each granule cell migrates using a Bergmann glia process as a guide, see text for explanation. (C) Histogram showing final lengths of the parallel fibers in the representative case, 300 μm is the maximum possible length for the simulation volume. (D) Bar plots showing success rates of soma radial migrations, of parallel fiber branching to form T-junctions, of parallel fiber extensions initiated in the main volume and of parallel fibers growing from the outside into the main volume and fully extending in the main volume. Mean success rates from 10 simulation samplings of the model with error bars showing standard deviations. Coefficient of variation values for each is 0.031, 0.007, 0.007, and 0.004 respectively. (E) Another side view (longitudinal side) of the granule cell model after all green granule cells finish migration. Black to gray stripes represent z-locations of granule cell births during 12 phases. The central part is the main simulation cube (panel A), left and right sides are origin sites of ingrowing parallel fibers. (F) Top view of the model with numbering of Purkinje cell somata. Brown cells were added to provide dendritic repulsion at the borders of the main simulation cube but were not analyzed. Blue structures are Bergmann somata and radial glia.