由感觉和交感节神经元组成的中枢外反射弧的形态学研究

用免疫细胞化学和辣根过氧化物酶（HRP）逆行追踪法研究了感觉神经节和交感神经节中P物质（SP）样免疫反应物的分布及两种神经节之间的联系。在所有背根节出现大量SP免疫阳性神经元胞体，但在胸交感干节和腹腔-前肠系膜神经节仅有大量的SP阳性纤维和终末，而无阳性胞体。分组切断与腹腔-前肠系膜神经节相联系的神经支后，该节内的SP免疫反应物仅在切断与背根节的联系后明显减少或消失。将HRP注入腹腔神经节，在同侧C8～L3背根节出现大量标记细胞。以上结果表明．在感节中的SP纤维和终末来自背根节初级传入神经元的轴突侧支，提示由初级传人神经元与交感节主细胞在中枢外直接形成了短反射环路。

A MORPHOLOGICAL STUDY ON AN EXTRA-CENTRAL REFLEX ARC FORMED BY NEURONS OF THE SENSORY-AND SYMPATHETIC GANGLIA

The distribution of SP - like immunoreactivity in the sensory and sympathetic ganglia, as well asthe fiber connection between sensory ganglia and sympathetic ganglia(SG) were studied by theimmunocytochemical technique and retrograde transportation of HRP. A large number of SP - like neurons were found in dorsalroot ganglia(DRG), where as in thoracic SG and coeliac- cranial mesenteric ganglion complex(CCMG), a largeumber of SP- like fibers and terminals were found, but no SP positive perikaryon was seen in those ganglia. Bycutting the various nerves connected with the CCMG complex, it has been demonstrated that the SPimmunoreactive material in the ganglion was only decreased obviously or disappeared when the fiber connection between theDRG and CCMG was severed. After injecting HRP into CCMG, a large number of labelled neurons were found inthe DRG of C8~L3 segments. The results indicate that SP - containing fibers and terminals present in the SG andCCMG came from collateral branches of primary sensory neurons in the DRG. It is suggested that a short - loopreflex arc outside the central nervous system exists, which was formed directly by primary afferent neuron andsympathetic ganglionic neuron.