Ultrastructure and synaptic connections of cutaneous afferent fibres in the spinal cord

The combination of intracellular recording and staining techniques with electron microscopy offers a unique opportunity for correlating physiological and ultrastructural properties of single neurones. The spinal terminations of cutaneous primary afferent fibres have been studied by this method, and examination of the ultrastructural synaptology of their boutons sheds light on how sensory information may be processed at the first synapse in the spinal cord. The combination of intracellular staining techniques with other neuroanatomical tract-tracing methods can reveal some of the neuronal networks of the spinal cord and, particularly, the contributions made by primary afferent fibres to these networks.