No abstract

Our purpose is to elucidate the roles of some molecules and DNA methylation in cerebellar development. Immunocytochemistry was performed to investigate the expression of activated Notch1 and Sonic Hedgehog (Shh), as well as DNA methylation during cerebellar development at various ages. Notch1 could be expressed in neural stem cells, newborn neurons and Purkinje cells during cerebellar development. However, Shh could be expressed mainly in developing radial glia or Bergmann cells specifically.

Neural migration is regarded as a key step for cortical development and cortical lamination. While classical theory holds that immature neurons migrate to their destinations along radial glia, there is some preliminary evidence showing that vasculature is probably involved in that process as well. In this study, we compared vascular development with that of radial glia and the migration of neurons, so that the relationships among them could be elucidated. We found that the radial glial cells and vasculature were highly similar in their distribution and development. For instance, in the external granular layer (EGL, the putative molecular layer), the processes of radial glial cells were arranged in an orderly radial pattern, whereas in the deep areas of the cerebellum, their arrangements were in relative disorder. On the other hand, the vasculatures in EGL were usually orientated radially, which paralleled the projections of radial glia; however, the distribution of vasculature in the internal granular layer (IGL, the putative granular layer) and white matter was in relative disorder as well, similar to the pattern exhibited by radial glial processes. This high harmonization between vasculature and radial glia suggests their interconnected biological relationships during cerebellar development and neural migration. We also observed that a large number of newborn neurons were migrating along blood vessels, suggesting that the vasculature could serve as a scaffold for cell migration. In conclusion, cerebellar vasculature could guide neural migration not only as a platform for biological interaction with radial glia, but also serve scaffolding functions for neural migration.