生长抑素样免疫反应物在山羊脊髓和背根节的分布─ABC法研究

DISTRIBUTION OF SOMATOSTATIN-LIKE IMMUNOREACTIVITY IN GOAT SPINAL CORD AND DORSAL ROOT GANGLION ──A STUDY WITH ABC METHOD

用免疫细胞化学ＡＢＣ法研究了生长抑素样免疫反应物在山羊脊髓和背根节的分布。在整个脊髓背角，出现浓密的生长抑素样纤维和终末网，在板层Ⅱ和Ⅲ形成不规则的波形带。在带的深面，大量的生长抑素阳性小细胞（直径小于１５μｍ）形成细胞带，这些细胞呈卵圆形或梭形，大多是双极细胞。在背角最表层仅有稀疏的生长抑素阳性纤维。这种分布型式显著不同于以前报道的其它动物。在胸髓中间外侧核有为数不多的生长抑素阳性细胞，在脊髓的其它部位如中间带区和腹角有少量散在纤维和终末。还发现纤细的生长抑素阳性纤维和终末网出现于骶髓中央管的背外侧区域。此外，在所有背根节只见到极少数生长抑素阳性神经元；切断背根时，相应节段的脊髓背角的生长抑素样免疫反应物无明显变化。本研究结果表明，山羊脊髓背角的生长抑素主要来源于脊髓背角的固有神经元，而不是背根节细胞。出现于脊髓板层Ⅱ和Ⅲ的生长抑素阳性神经元可能属于岛细胞。本研究还提示，生长抑素可能在脊髓的感觉和内脏运动系统中起作用，还表明生长抑素免疫反应物的分布存在着种属差异。

The distribution of somatostatin(SS)-like immunoreactivity in the goat spinal cord and dorsal root ganglion was studied by using the immunocytochemical ABC method without colchicine adminstration to block the axonal transport. A very dense network of SS-positive fibers and terminals, forming an irregular wave-shaped band, was found in the lamina Ⅱ and Ⅲof the dorsal horn at all levels. A large number of the small SS-positive perikarya (less than 15um in diameter), forming a cell band, was located ventral to the fiber band closely, these neurons are oval or fusiform shaped, the majority of them are bipolar cells. Sparse SS-fiber were also observed in the most superficial layer of the dorsal horn. This distribution pattern is different from that in other species reported before. A few SS-positive neurons were seen in the intermediolateral nucleus of the thoracic cord. Fine network of SS-containing fibers and terminals were observed dorsolateral to the central canal on both sides at the sacral segment only. In other regions, including the ventral horn, the intermediate zone and the central gray area, there is a sparse population of SS-containing fibers and terminals at all levels. In addition,very few SS-positive neurons were seen in all dorsal root ganglia examined. Following dorsal root section,the SS-like immunoreactivity within the relevant segment of the spinal cord was unchanged obviously.The results indicate that the major source of somatostatin within the dorsal column is the local intrinsic neurons of the spinal cord itself. not the primary sensory neuron in the dorsal root ganglia,those SS-positive neurons on Raxed laminae Ⅱ and Ⅲ of the spinal cord at all levels may possibly be islet cells named by Gobel. It seems reasonable to suggest that SS probably plays a role in the sensory and visceromotor systems of the spinal cord, and also species-related differences of the distribution of the SS-like immunoreactivity are present.