Differentiation of Purkinje cells in cerebellar slice cultures: an immunocytochemical and Golgi EM study.

In the rat central nervous system, the cerebellar cortex has a stereotypical cytoarchitecture and a characteristic connectivity pattern, both mainly formed post-natally. Organotypic cultures of immature cerebellar tissue were used to study the formation of the cerebellar lamination and the differentiation of Purkinje cells in the absence of their extracerebellar afferents. The lamination was retained in the majority of the cerebellar cultures and most Purkinje cells were aligned. Axonal profiles of Purkinje cells, immunolabelled for UCHT1 or anti-calbindin D-28 k, followed pathways similar to those in vivo cerebellum. The dendrites were orientated towards the superficial layer except of those neurons which were ectopically positioned. Unlike in vivo, the dendritic arborization of Golgi-impregnated/gold-toned or immunostained Purkinje cells was reduced and the dendritic spines were often elongated. Somatic spines, a morphological feature of immature Purkinje cells persisted even after 4 weeks in culture. We conclude that the Purkinje cells in organotypic cultures send their axon to the correct target region independent of their local position. In contrast, the dendritic orientation and differentiation is influenced by the cellular environment and by specific synaptic interaction.