ULTRASTRUCTURE OF THE LATERAL HORN IN THE MID-THORACIC CORD / 解剖学报

ABSTRACT

The ultrastructural characteristics of the lateral horn of the cat and rat revea-led by present study included(1)The neurons of cell clusters in the lateral hornwere fusiform or oval,oriented rostrocaudally and possessed similar fine structures.The dendrites often protruded from the rostral and caudal poles of the cell bodies.The synapses on neuronal somata were sparse,for usually only 0-5 buttons contac-ted the plasmalemma in each neuronal profile.A little amount of neuropil existedbetween cell bodies in the cell clusters,even sometimes the plasma membranes ofadjacent cell bodies apposited directly.(2)Most dendrites in the lateral horn ranlongitudinally and paralleled with one another.Numerous dendrites aggregated inthe ventral part of the cell clusters,constituting a dendrite bundle in which adja-cent dendrites apposited directly and were surrounded by glial processes.(3)Manyunmyelinated fibers and fiber bundles ran longitudinally in the lateral horn.Theywere parallel with the neuronal and dendritic profiles.Unmyelinated fiber bundlesconsisted of the fibers with diameter less than one micron,and their terminal bottonsoften compacted together.(4)The majority of the synapses in the lateral horn wereaxodendritic synapses.A small number of axosomatic and axoaxonic synapses werefound,occasionally synaptic glomeruli and serial synapses were observed.Most ofthe buttons contained round clear vesicles and some plus a few granular vesicles.