FIGURE 2.

Developmental origin of major types of cerebellar neurons. (A) Diagram of a sagittal section of the mouse embryonic cerebellar anlage (e10.5-e18) showing that the cerebellar rhombic lip (cRL) gives rise to excitatory cerebellar cells, namely granule cell precursors (GCP), unipolar brush cells (UBC), and excitatory neurons of the cerebellar nuclei (CN). The cerebellar ventricular zone (cVZ) gives rise to inhibitory cells, such as Purkinje cells (PC), inhibitory interneuron progenitors (IIP) and inhibitory neurons of CN. Tangentially migrating GCPs form the secondary germinal zone—the external granule cell layer (EGL). (B) Diagram of a midsagittal section of the neonatal mouse cerebellum, showing layered organization of the cerebellar cortex. (C) Higher magnification of the region boxed in panel (B). After transient amplification in the EGL, GCPs differentiate into granule cells (GC) and migrate radially along Bergmann glial fibers (shown as black lines) from the EGL to the IGL. External granule cell layer—EGL; Molecular layer—ML; Purkinje cell layer—PCL; internal granule layer—IGL; white matter—WM. The anterior-posterior (A–P) and dorsal-ventral (D–V) axes are shown in the top left corner of panels (A) and (B).