ラット上頸神経節節前細胞の脊髄内局在および大きさについて

Abstract

We investigated localization and size of preganglionic neurons in the spinal cord supplying to the superior cervical ganglion (SCG) by using horseradish peroxidase (HRP) method. We also payed attention to possibility of interganglionic projection from the contralateral SCG, the stellete (SG) or the trigeminal ganglia (TRG). 40 % HRP (1μl) was injected into the SCG of anesthetized Wistar rats. After 48-hour survival period, animals were perfused with fixative and the spinal cord, SCG and SG were dissected out, sectioned and processed with tetramethyl benzidine method. Neutral red solutions was employed as counterstain. Labeled cells were recognized only at the ipsilateral side to the HRP application and were restricted to the spinal segments C₈-T₅. More than 70 % of them were located in T₁-T₂ segments (Table 1). They were localized in three regions of the spinal cord ; the inter- mediolateral nucleus (IML : 91.7 %), lateral funiculus (LF : 8.0 %o) and intercalated region (IC : 0.3 %), but no labeled cells in the central autonomic nucleus (CA) (Table 2). Labeled cells were small ; their mean diameter was 12.3±2.0μm. No labeled cells existed in the contralateral SCG, or bilateral SG or TRG. These results suggest that most of preganglic neurons projecting to SCG localize in IML of the spinal segment T₁, T₂. No trigeminal sensory neurons are directly blocked by cervical sympathetic block, because of trigeminal fibers not projecting to SCG. There are no innervating fibers from SCG of the contralateral side or SG.