Fine structure of collateral axons originating from feline spinocervical tract neurons

In adult cats, 7 spinocervical tract neurones were intracellularly labelled with horseradish peroxidase and ultrastructural properties of collateral axons of 3 of them were examined. The terminations of collateral axons formed boutons which made synaptic associations predominantly with the somata and proximal dendrites of dorsal horn neurones. Collateral axons of one spinocervical tract neurone formed synaptic associations with a cell which projected via the dorsal columns.