Cell and neuropil architecture of the intermediolateral (sympathetic) nucleus of cat spinal cord

Abstract

A Golgi study of the neuronal elements in the thoracic intermedio-lateral nucleus (preganglionic sympathetic neuronal column) is presented, with some additional electron microscopic observations. The dendrites of the sympathetic neurons are strictly longitudinally oriented; their axons can be traced along the border between the ventral horn and the lateral funiculus directly into the ventral rootlers. No initial collateral of the axons can be observed. The neuronal population of the intermedio-lateral nucleus is entirely homogeneous and little contaminated by dendrites of other cells. The axonal neuropil of the nucleus is also longitudinally oriented and is fed mainly from collaterals of the lateral funiculus. The synaptic arrangement between the axonal and dendritic arborizations is mainly of the ‘climbing type’. Three different kinds of synaptic terminals can be recognized in the electron microscope picture: (1) terminals containing an unusually large number of large osmiophilic vesicles and apparently clear ordinary vesicles; (2) terminals (often axo-somatic) containing characteristic flattened vesicles; and (3) axo-dendritic terminals containing clear spherical synaptic vesicles.