Arrangement of dendrites and morphological characteristics of sympathetic preganglionic neurones projecting to the superior cervical ganglion and adrenal medulla in adult cat

Abstract

Sympathetic preganglionic neurones (SPN) projecting to the superior cervical ganglion (SCG) and adrenal medulla (AM) in the adult cat were retrogradely labelled with cholera B horseradish peroxidase (CBHRP). Labelled neurones were found in 4 sub-nuclei: the nucleus intermediolateralis thoracolumbalis pars principalis (ILp), the nucleus intermediolateralis pars funicularis (ILf), the nucleus intercalatus spinalis (IC) and the nucleus pars paraependymatis (ICpe). The majority of SPN were found in the ILp (75%). Each group of target specified SPN had a different segmental distribution. SCG-SPN between cervical 8 (C8) and thoracic 6 (T6) and AM-SPN between thoracic 3 (T3) and lumbar 2 (L2). Fusiform and round bodied neurones were the most common shapes found, a third longitudinal type was occasionally found. SCG and AM-SPN exhibited a dense rostrocaudal dendritic projection extending along the length of the ILp. There was also a lateral projection into the ILf and a medial one projecting towards the central canal. This dendritic arrangement gave the ILp the appearance of being an ‘open nucleus’. The dendrites branched at their distal ends and all along their lengths swellings could be seen. It was concluded that contrary to previous descriptions the arrangement of SPN in the adult cat is not too dissimilar to that in the adult rat.