Timetables of neurogenesis in the development of the cerebellum

© 2018 Nova Science Publishers, Inc. The cerebellum is a region of the vertebrate nervous system involved in functions such as motor coordination, perception, cognition and development of the language. The anatomical structure of the adult cerebellum consists of a three-layered cortex and a set of cerebellar nuclei embedded in the white matter. There is evidence indicating that the germinal source of cerebellar neurons is heterogeneous. GABAergic neurons, such as inhibitory interneurons and some deep neurons, originate from the cerebellar neuroepithelium. On the other hand, glutamatergic neurons, including deep cerebellar nuclei neurons and unipolar brush cells, arise from progenitors located in the anterior rhombic lip. Granule cell precursors also originate from the rhombic lip and migrate tangentially over the surface of the cerebellar anlage to form the external granular layer As indicators of DNA synthesis, tritiated thymidine and 5-bromo-2'- deoxyuridine have shown that one of the most important features of the cerebellar development is that each neuronal population is generated during a specific temporal window. This is named timetable of neurogenesis or time of neuron origin. It allows for an accurate delineation of both the onset and cessation of neurogenesis as well as for the determination of the proportion of neurons that are produced during single days of embryonic or postnatal life. We will show here that several types of cerebellar neurons are generated sequentially: first, the output neurons (deep neurons and Purkinje cells) and then, the interneurons (Golgi, unipolar brush, basket, stellate and granule cells).