The effect of lesions in the neural crest on the formation of synaptic connexions in the embryonic chick spinal cord

1. The pattern of synaptic activity in lateral gastrocnemius (l.g.) motoneurones in the lumbar spinal cord of chick embryos (Stage 44‐45, 19‐21 d of incubation) has been examined using intracellular recording. In the motoneurones of normal chick embryos, stimulation of different peripheral, sciatic nerve branches gave rise to characteristic synaptic responses. Stimulation of the lateral gastrocnemius nerve caused a monosynaptic e.p.s.p. which was graded by the intensity of nerve stimulation. Stimulation of synergistic muscle afferents also caused a brief latency e.p.s.p., followed by longer latency excitatory and inhibitory synaptic potentials. Stimulation of antagonistic muscle afferents or cutaneous afferents gave rise to longer latency inhibitory and excitatory synaptic potentials respectively.

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