[Morphogenesis of neuronal systems in tissue culture repeats the evolution of simpler nervous systems]

Comparison of simpler nervous systems of invertebrates and plexiganglionic systems cultivated in tissue culture was conducted for the first time. Their principal resemblance was discovered. By following up the kinetics of neuronal behaviour in culture similarity between mechanisms underlying the evolution of simpler nervous systems and processes of self assembly of neuronal systems was revealed. In both cases isolated nerve cells are replaced by primitive (archaic) nervous plexus that, in turn, becomes a plexiganglionic neuronal system. Final individual architecture of ganglia and mechanisms of formation of nerve ganglia and trunks coincide. Highly specialized unipolar neurons transform into archaic unipolar cells and display signs of chemotaxis. Resemblance of stages and mechanisms of the formation of all elementary nervous systems and neuronal systems in culture is explained by integrity of the neuron properties (adhesion and mobility of neuron bodies, extrusion and retraction of their processes and autotomy of nerve endings). Similar neuron potentialities in evolution and tissue culture underly the abundance of parallelisms between nervous systems in animals of unrelated phyla. In this aspect a possibility appeared to formulate another biogenetic postulate concerning general mechanisms of neurogenesis: morphogenesis of plexiganglionic neuronal systems in tissue culture represents fast and simplified repetition of the evolution of elementary nervous system of invertebrates.