ULTRASTRUCTURE AND FUNCTION IN NEUROHYPOPHYSIS OF THE TOAD
ULTRASTRUCTURE AND FUNCTION IN NEUROHYPOPHYSIS OF THE TOAD
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DOI：
10.1210/endo-66-5-741
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发表时间：
1960-01-01
期刊：
影响因子：
4.8
通讯作者：
DEROBERTIS, E
中科院分区：
文献类型：
--
作者：
GERSCHENFELD, HM;TRAMEZZANI, JH;DEROBERTIS, E
电子显微镜研究进行了下丘脑部分的视前神经垂体束和漏斗过程中的蟾蜍在正常的水平衡或实验处理，以产生垂体后叶激素的释放。含有神经分泌颗粒的轴突已被观察到在下丘脑（区域I）中的漏斗突的门（区域n），毛细血管附近（区域III）和适当的结束（区域IV）。神经分泌颗粒形成于特殊的致密囊泡内，具有高电子密度，并被包膜包围。它们的尺寸从I区的620 A增加到II区和III区的1350 A-1500 A。在末端（IV区）出现了第二个成分，与De Robertis和班尼特（1954）描述的突触囊泡相似。囊泡的平均大小为420埃，直方图显示这些成分之间没有重叠。在区域I至III的轴突内观察到神经原纤维和更细的神经丝。在轴突的所有部分都有形状奇怪的线粒体，它们与神经分泌物质无关。在慢性脱水的动物中，神经分泌颗粒从末梢消失，但在轴突的其他区域持续存在。在末端，突触囊泡保留下来，并且在慢性脱水后似乎数量增加。在急性脱水的动物（注射高渗NaCl），大多数神经分泌颗粒消失，只有一些空的膜观察到的结束。在这种情况下，突触囊泡的数量似乎也减少了。乙醚麻醉产生大量神经分泌物的释放和神经末梢的空泡化。根据我们的研究结果讨论了神经分泌轴浆流的概念。它的结论是，除了流的分泌物应该有一个渐进的合成材料沿着轴突。可能的机制进行了讨论，并与其他神经体液分泌过程中的机制进行了比较。提出了突触小泡在神经分泌纤维功能中可能发挥的作用的假说。
An electron microscope study was carried out on hypothalamic portions of the preoptic-neurohypophyseal tract and in the infundibular process of toads in normal water balance or treated experimentally to produce release of the posterior pituitary hormones. Axons containing neurosecretory granules have been observed in the hypothalamus (region I) in the hilum of the infundibular process (region n), near the capillaries (region III) and at the ending proper (region IV). The neurosecretory granules, that are formed within special dense vesicles, have a high electron density and are surrounded by an enveloping membrane. Their size increases from 620 A in region I to 1350 A-1500 A in regions II and HI. At the ending (region IV) a second component appears which is similar to the synaptic vesicles described by De Robertis and Bennett (1954). The mean size of the vesicles is of 420 A and the histograms show no overlapping between these components. Within the axons of region I to III neuroprotofibrils and finer neuro-filaments are observed. In all parts of the axons there are bizarrely shaped mitochondria that bear no relationship to the neurosecretory material. In chronically dehydrated animals the neurosecretory granules disappear from the endings but persist in other regions of the axon. At the endings the synaptic vesicles remain and appear to increase in number after chronic dehydration. In acutely dehydrated animals (injection of hypertonic NaCl) most neurosecretory granules disappear and only some empty membranes are observed at the endings. In this case also the synaptic vesicles seem to decrease in number. Ether anesthesia produces a massive release of neurosecretion and vacuo-lization of the nerve endings. The concept of axoplasmic flow of neurosecretion is discussed on the basis of our findings. It is concluded that in addition to the streaming of secretion there should be a progressive synthesis of material along the axon. The probable mechanisms of release are discussed and compared with those in other neurohumoral secretory processes. A hypothesis is advanced about the possible role played by the synaptic vesicles in the function of neurosecretory nerve fibers.