Macroscopical and Histological Aspects of the Cerebellum in Chinchillas

In view of the relatively recent introduction of the chinchilla as an experimental model in human neurological research, there rises a need for a precise knowledge of the anatomy and structure of the different segments composing this species’ encephalon. Our study aimed to enrich the current data pool, by providing a macroscopical and histogical description of the chinchilla's cerebellum. 10 samples were harvested from commercially slaughtered young adults of both sexes. 5 samples were macroscopically examined and 5 samples were serially cut and stained (both Hematoxylin-Eosin and a modified Luxol-Cresyl protocol). The external features and the structure of the cerebellum were assessed and compared to literature data on other similar species (such as the rat and the rabbit). The macroscopic examination revealed that the chinchilla's cerebellum is well developed in size (average width of 2 cm) relative to the size of the encephalon (average width of 2.4 cm). The cerebellar hemispheres are globulous, with a prominent paraflocculus and the vermis is very thick. The ratio between these segments resembles that of the rabbit's. Histological samples revealed that the cerebellar cortex presents the main layers common for cerebellar cytoarchitectonics. The segmentation of the vermis is similar to that o the rat, but there are variations in lobular size, lobular orientation and placement of the primary and secondary fissures. Our results indicate that, although the structure of the chinchilla's cerebellum generally complies to rodent literature descriptions, experiments demanding stereotaxic location of lobules and foliae cannot completely rely on the existing neuroanatomic maps of other species (such as the rat), benefiting from the present description.