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Development of the cerebellar afferent system in the shark Scyliorhinus canicula : Insights into the basal organization of precerebellar nuclei in gnathostomes
Author(s) -
PoseMéndez Sol,
Candal Eva,
Adrio Fátima,
RodríguezMoldes Isabel
Publication year - 2013
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.23393
Subject(s) - biology , scyliorhinus canicula , pretectal area , cerebellum , anatomy , reticular formation , deep cerebellar nuclei , neuroscience , nucleus , cerebellar cortex , midbrain , central nervous system , fishery , fish <actinopterygii>
The cerebellum is recognized as an evolutionary innovation of jawed vertebrates, whose most primitive group is represented by the chondrichthyans, or cartilaginous fishes. A comprehensive knowledge of cerebellar connections in these fishes might shed light on the basal organization of the cerebellar system. Although the organization of the precerebellar system is known in adults, developmental studies are essential for understanding the origin and evolution of precerebellar nuclei. In the present work we performed a developmental study of cerebellar connections in embryos and juveniles of an advanced shark species, Scyliorhinus canicula , by application of tract tracing in combination with immunohistochemical techniques. Main precerebellar cell populations were located in the diencephalon (pretectum and thalamus), mesencephalon (reticular formation and nucleus ruber), rhombencephalon (cerebellar nucleus, reticular formation, and inferior olive), and spinal cord (ventral horn). The order of arrival of cerebellar afferent projections throughout development revealed a common pattern with other jawed vertebrates, which was helpful for comparison of stages of cerebellar development. The neurochemical study of the inferior olive and other precerebellar nuclei revealed many shared features with other gnathostomes. Furthermore, because many precerebellar nuclei originate from rhombic lips, the first analysis of neuronal migrations from these lips was performed with markers of neuroblasts. The shared features of development and organization of precerebellar connections observed between sharks and amniotes suggest that their basic pattern was established early in gnathostome evolution. J. Comp. Neurol. 522:131–168, 2014. © 2013 Wiley Periodicals, Inc.