The corticotectal projection of the rat established in organotypic culture.

To study the mechanisms involved in the formation of neural projections we established an in-vitro model system, consisting of the projection from visual cortex (VC) to colliculus superior (SC) in organotypic slice culture. The typical laminar structure of both brain areas was well conserved in-vitro. A projection from VC to SC was reliably formed. Cortical projection neurons retrogradely stained by DiI were situated in layer V and showed a prominent apical dendrite with a tuft in layer I. No projection from SC to VC was established. Cortical terminal arborizations revealed by anterograde staining were often organized in layers. We conclude that the typical anatomical characteristics of the corticotectal projection are preserved in-vitro.