Bergmann Glia and the Recognition Molecule CHL1 Organize GABAergic Axons and Direct Innervation of Purkinje Cell Dendrites
Figure 9
Schematic Representation of the Bergmann Glial Fiber Scaffold and CHL1 in Directing Stellate Axons to Innervate Purkinje Dendrites
(A) In the cerebellar cortex, Purkinje dendrites (yellow) are restricted in the translobular plane. Each BG cell (red) gives rise to several ascending BG fibers, which extend in both the translobular and parlobular plane [14,15]. These largely radial fibers from neighboring BG cells further aligned into thin walls, or palisades, in the parlobular plane, perpendicular to the Purkinje dendrites. As a consequence, several BG palisades cut across and impinge upon an individual Purkinje dendrite in a largely vertical orientation.
(B) A stellate axon likely contacts segments of multiple intercalated Purkinje dendrites (parlobular view; neighboring Purkinje dendrites are represented in different shades of yellow). Stellate synapses (blue dots) are formed or stabilized at the interception of BG fibers and Purkinje dendrites.
(C) In the translobular plane in WT mice (left panel), stellate axons (green) associate with and extend along BG fibers, and are thus organized into characteristic orientations and trajectories towards Purkinje dendrites. In CHL1-deficient mice (right panel), stellate axons can no longer associate with BG fibers, show aberrant orientation and trajectory, and are deficient in synapse formation and/or stability.