Ontogeny of visinin-like immunoreactive structures in the rat cerebellum and vestibular nuclei: an immunohistochemical analysis.

The ontogeny of visinin-like immunoreactive (visinin-IR) structures in the cerebellum and vestibular nuclei of the rat brain was examined by indirect immunofluorescence. Visinin-IR structures are localized exclusively in the Purkinje cell system in these areas. Immunoreactive Purkinje cells first appear at gestational day 18, increasing in number with age. The axons appear at gestational day 19 and develop markedly until reaching the adult level at postnatal day 4. However, immunoreactive dendrites do not reach the adult pattern until postnatal day 21. In the cerebellar and vestibular nuclei, immunoreactive fibers first appeared at gestational day 18 and increased in number there with age, reaching the adult level at postnatal day 4.