Ultrastructural morphology of axon terminals of an inhibitory spinal interneurone in the cat.

Axon collateral terminals of an interneurone mediating Ia reciprocal inhibition of spinal a-motoneurones have been ultrastructurally investigated after intracellular staining with horseradish peroxidase. The size of bouton profiles, the size and shape of synaptic vesicles and the characteristics of synaptic contacts were analyzed in 38 terminals. The morphology of the terminals was compared with the morphology of previously investigated terminals of excitatory spinocervical tract cells.

Quantitative analysis of axodendritic and axosomatic collateral terminals of two feline spinocervical tract cells.

The initial axon collaterals of two feline spinocervical tract cells have been ultrastructurally investigated after intracellular injection with horseradish peroxidase. A total of 200 axodendritic and 43 axosomatic terminals were analysed in serial section. The following variables were measured: the diameter and area of the bouton profiles, the areal densities of synaptic vesicles and mitochondria of the bouton profiles, the width and length of the synaptic clefts, the width of the postsynaptic densities, the width of the postsynaptic dendrites, and the width and length of axons between the boutons.

Morphology of synaptic vesicles in axo-dendritic and axo-somatic collateral terminals of two feline spinocervical tract cells stained intracellularly with horseradish peroxidase.

Synaptic vesicles in initial collateral terminals of two feline spinocervical tract cells have been investigated after intracellular staining with horseradish peroxidase. A total of 5325 vesicles in 52 axodendritic and 26 axo-somatic terminals were analysed after aldehyde-osmium fixation. The greatest length and longest perpendicular width of each vesicle were measured, and the ratio and geometric mean of the diameters (gm-diameters) were calculated.

Segmental and supraspinal input to cells of origin of non-primary fibres in the feline dorsal columns.

1. The synaptic input to ascending tract cells with axons in the dorsal columns was investigated using intracellular recording. 2.

Arborization of initial axon collaterals of spinocervical tract cells stained intracellularly with horseradish peroxidase.

The initial axon collateral arborizations of two feline spinocervical tract cells have been analysed after intracellular staining with horseradish peroxidase. The images of the cells were reconstructed in the light microscope from transverse serial sections. The cell bodies were situated in laminae IV or III of the lumbar dorsal horn.