Axonal anatomy of molecular layer heterotopia of the cerebellar vermis

► Heterotopia of the cerebellar vermis in C57BL/6 mice contain diverse axonal afferents. ► Myelinated and Thy1-YFP labeled axons innervate heterotopia. ► 5HTT-, ChAT-, and TH-labeled axons innervation heterotopia. C57BL/6 mice and closely related strains exhibit heterotopia in the molecular layer of folia VIII and IX of the cerebellar vermis. Previously, we demonstrated that heterotopia are composed primarily of granule cells, Golgi cells, and GABAergic interneurons and are indicative of neuronal migration defect. In the present report we use immunocytochemistry and Thy1-YFP reporter mice to reveal the axonal constituents of cerebellar heterotopia which include mossy fibers, as well as serotonergic, cholinergic, and catecholaminergic axons. These data are relevant toward understanding of the mechanisms of axonal targeting during normal and abnormal cerebellar development.