Prenatal Cerebellar Ontogenesis

Although the ontogeny of the cerebellum has been studied with cytological techniques for more than two centuries, it is still of extended clinical importance in the basic neuroscience as the explanation of the mechanisms driving cerebellar neurogenesis is relevant to clinical neuroscience. This study is an attempt to perform a thorough morphological investigation of the cerebellum development during the prenatal period. The rat was the animal model of this work and the embryonic period covered in it, was from the embryonic day 15 till birth. We used the E-designation system to determine the relevant developmental stages of (62) rat embryos. For the general histological study, serial sections of paraffin blocks of the embryonic tissues were stained with H& E stain and for the neurohistological study, they were stained with Nissl and Bielschowsky's Silver stains. The results of the present study revealed that major morphogenetic events take place during prenatal cerebellar ontogenesis including the formation of the Rhombencephalic demilune, external granular layer, migration and settlement of the Purkinje cells, primitive cerebellar cortex and 1st stage of the foliation. This work concluded that hallmark of the major morphogenetic events that take place during prenatal cerebellar ontogenesis is the migration of Purkinje and granular cell precursors.