Golding D W, Pow D V
Department of Biology, University of Newcastle upon Tyne, England.
Neuroendocrinology. 1990 Apr;51(4):369-75. doi: 10.1159/000125363.
Nerve fibers within the large pancreatic islet of Xiphophorus helleri are apparently of a single type and form typical, well-differentiated synapses with the endocrine gland cells. A histochemical test for cholinesterases generates reaction product in association with the outer surfaces of the neuronal membranes. Two categories of presumptive secretory inclusions are present in the fiber terminals: secretory granules usually 80-120 nm in diameter have a wide distribution within the fibers, whereas electron-lucent synaptic vesicles 30-60 nm across often cluster adjacent to membrane thickenings and differentiated clefts. Infusion of tannic acid in high-K+ saline enabled sites of granule exocytosis to be visualized. These presumed sites of neuropeptide discharge were associated with morphologically undifferentiated regions of the terminal membranes. Tannic acid also facilitated the detection of exocytosis, involving granules of endocrine gland cells; discharged secretory material exposed to this agent retains immunoreactivity at a reduced level.
剑尾鱼大型胰岛内的神经纤维显然属于单一类型，并与内分泌腺细胞形成典型的、分化良好的突触。胆碱酯酶的组织化学检测在神经元膜外表面产生反应产物。纤维终末存在两类假定的分泌性内含物：通常直径为80 - 120纳米的分泌颗粒在纤维内分布广泛，而直径30 - 60纳米的电子透明突触小泡常常聚集在膜增厚处和分化的裂隙附近。在高钾盐溶液中注入鞣酸可使颗粒胞吐部位可视化。这些假定的神经肽释放部位与终末膜形态未分化区域相关。鞣酸还促进了对内分泌腺细胞颗粒胞吐作用的检测；暴露于该试剂的已排出分泌物质在较低水平保留免疫反应性。
