[Morphofunctional development of the hippocampal formation of newborn mice in organotypical tissue culture].

The cytoarchitectonic structures, fiber pathways, spontaneous and evoked neuronal activity in the organotypic explants of the newborn mouse hippocampus were studied. After 2-3 weeks in vitro it was possible to see in the explants main fascicles (alvear tract, perforant path, axons of granular cells) and cytoarchitectonic formations (pyramidal cell layer of hippocampus, infra- und suprapyramidal limbs of dentate gyrus granular cells). Electrical stimuli applied to the entorhinal cortex and fascia dentata evoked short- and long-latency responses in hippocampal neurons beginning from the 5-6th day in vitro. The short-latency responses were presumably monosynaptic, the long-lasting ones, polysnaptic. The latter were usually changed by repetitive stimulation. These data suggest that appearance of evoked activity during cultivation reflects the formation in vitro of the perforant path and mossy fibers and the maturation of the synaptic contacts. Thus, organotypic explants of the hippocampus represent a useful model system for morphological and electrophysiological studies in systems of interneuronal connections formed de novo as a result of autonomical postnatal development in vitro.