Réthelyi M, Light A R, Perl E R
J Comp Neurol. 1982 Jun 1;207(4):381-93. doi: 10.1002/cne.902070409.
The individual fine myelinated fibers of cutaneous mechanical nociceptors and "D-hair" receptors were identified by electrophysiological recording with micropipette electrodes in cats and monkeys. Their intraspinal terminations were labeled by iontophoresing horseradish peroxidase intracellularly and subsequent diaminobenzidine histochemistry. These terminations were examined with light and electron microscopy to determine the nature and organization of their synaptic contacts. Myelinated fibers of the mechanical nociceptors became unmyelinated before exhibiting many enlargements that made multiple synaptic contacts in the marginal zone (lamina I) and lamina V. Pre- or postsynaptic contacts were found only on enlargements. In the marginal zone of the cat, enlargements made simple axodendritic contacts or were scalloped, central terminals in glomeruli. In glomeruli, myelinated mechanical nociceptor enlargements were presynaptic to several dendritic appendages and postsynaptic to two different types of profiles. One type was interpreted as a presynaptic axon terminal, the other as a presynaptic, vesicle-containing, dendritic appendage. In lamina V of the cat the nociceptor synaptic complexes were similar, but simpler, and only axonal profiles were found to be presynaptic to them. In the monkey marginal zone and deep nucleus proprius, myelinated nociceptor terminations formed the central element of glomeruli, which consisted of postsynaptic dendritic appendages and presynaptic axon terminals. D-hair axons terminated in large numbers of enlargements in the nucleus proprius (laminae III and IV) and inner substantia gelatinosa (lamina IIi). Their large rounded enlargements formed the central terminals in glomeruli and were presynaptic to both ordinary and vesicle-containing dendritic appendages; the presynaptic dendritic profiles also often contacted each other. Profiles interpreted as axonal in origin were the only terminals presynaptic to the primary ending within the D-hair glomeruli. The results suggest that transfer of primary afferent information occurs only at enlargements of the primary fiber and that each primary fiber enters into more than one kind of synaptic arrangement. They also point out that synaptic glomeruli are common to functionally different types of primary afferent fibers and that the internal organization of glomeruli varies with the kind of primary fiber and the locus of the complex.
通过使用微电极在猫和猴子身上进行电生理记录，鉴别出了皮肤机械性伤害感受器和“D型毛”感受器的单根细有髓纤维。通过细胞内离子电泳辣根过氧化物酶以及随后的二氨基联苯胺组织化学方法，标记了它们在脊髓内的终末。利用光学显微镜和电子显微镜检查这些终末，以确定其突触联系的性质和组织方式。机械性伤害感受器的有髓纤维在出现许多膨大之前会变为无髓，这些膨大在边缘层（I层）和V层形成多个突触联系。仅在膨大处发现了突触前或突触后联系。在猫的边缘层，膨大形成简单的轴突-树突联系或呈扇形，是肾小球中的中央终末。在肾小球中，有髓机械性伤害感受器的膨大对几个树突附属物是突触前的，对两种不同类型的轮廓是突触后的。一种类型被解释为突触前轴突终末，另一种为含囊泡的突触前树突附属物。在猫的V层，伤害感受器突触复合体相似但更简单，仅发现轴突轮廓是其突触前成分。在猴子的边缘层和深固有核中，有髓伤害感受器终末形成了肾小球的中央成分，肾小球由突触后树突附属物和突触前轴突终末组成。D型毛轴突在固有核（III层和IV层）和内胶状质（IIi层）中有大量膨大终末。它们的大圆形膨大形成肾小球中的中央终末，对普通的和含囊泡的树突附属物都是突触前的；突触前树突轮廓也经常相互接触。被解释为起源于轴突的轮廓是D型毛肾小球内初级终末的唯一突触前终末。结果表明，初级传入信息的传递仅发生在初级纤维的膨大处，且每根初级纤维参与不止一种突触排列。它们还指出，突触肾小球对于功能不同类型的初级传入纤维是常见的，并且肾小球的内部组织随初级纤维的种类和复合体的位置而变化。
