[Morphological bases of motor neuron interaction in the isolated spinal cord of rat pups studied with horseradish peroxidase].

The structure of connections of the lumbar motoneurons was investigated in the isolated spinal cord of young rats by the HRP methods. HRP was applied to the ventral roots and injected intracellularly into the motoneurons. The light microscopic study has shown that dendrodendritic, dendrosomatic and somatosomatic contacts between motoneurons might be established. Recurrent collaterals of motor axons were revealed. They were found to form contacts on the motoneuron dendrites and perikarya. The course and terminal arborizations of the ventral root afferent fibre were also described. The obtained morphological data related to electrophysiological analysis of motoneuronal postsynaptic potentials evoked by ventral root stimulation are discussed.