[Formation of functional synaptic connections between heterogeneous brain structures in an organotypic nerve tissue...

A directed growth of nervous fibres and formation of functional synaptic connections between heterogeneous brain structures (spinal cord and olfactory bulb of mouse embryos) were studied in organotypic nervous tissue culture by means of neuromorphological and neurophysiological methods. Within the first week in vitro fibre connections between the spinal cord and olfactory bulb explants were formed as glioneuritic bridges. In the formation of these connections glial cells play an active role and organize an oriented substrate upon which there occur growth and fasciation of axons developing later. Silver impregnation showed that connections between the explants were formed by bundles of axons or by separate nerve fibres. An electrophysiological study of the co-cultured heterogeneous brain structures revealed that functional synaptic connections were developed between the spinal cord and olfactory bulb explants by the second week of cultivation. Electrical stimuli applied to the spinal cord explants evoked short- and long-latency responses of neurons in the olfactory bulb explants. The described formation of nonspecific for the given brain structures functional synaptic connections in vitro showed a high degree of morphogenetic plasticity of growing or regenerating axons and an active role of neuroglial cells in a directed growth of nervous fibres.