Purdue University, Department of Psychological Sciences, West Lafayette, IN 47907-2081, United States.
Purdue University, Department of Psychological Sciences, West Lafayette, IN 47907-2081, United States.
Auton Neurosci. 2014 Jul;183:36-48. doi: 10.1016/j.autneu.2014.02.008. Epub 2014 Mar 6.
The pylorus is innervated by vagal mechanoreceptors that project to gastrointestinal smooth muscle, but the distributions and specializations of vagal endings in the sphincter have not been fully characterized. To evaluate their organization, the neural tracer dextran biotin was injected into the nodose ganglia of rats. Following tracer transport, animals were perfused, and their pylori and antra were prepared as whole mounts. Specimens were processed to permanently label the tracer, and subsets were counterstained with Cuprolinic blue or immunostained for c-Kit. Intramuscular arrays (IMAs) in the circular muscle comprised the principal vagal afferent innervation of the sphincter. These pyloric ring IMAs were densely distributed and evidenced a variety of structural specializations. Morphometric comparisons between the arbors innervating the pylorus and a corresponding sample of IMAs in the adjacent antral circular muscle highlighted that sphincter IMAs branched profusely, forming more than twice as many branches as did antral IMAs (means of 405 vs. 165, respectively), and condensed their numerous neurites into compact receptive fields (∼48% of the area of antral IMAs) deep in the circular muscle (∼6μm above the submucosa). Separate arbors of IMAs in the sphincter interdigitated and overlapped to form a 360° band of mechanoreceptors encircling the pyloric canal. The annulus of vagal IMA arbors, putative stretch receptors tightly intercalated in the sphincter ring and situated near the lumen of the pyloric canal, creates an architecture with the potential to generate gut reflexes on the basis of pyloric sensory maps of high sensitivity and fine spatial resolution.
幽门由迷走神经机械感受器支配，这些感受器投射到胃肠道平滑肌，但支配括约肌的迷走神经末梢的分布和特化尚未完全描述。为了评估它们的组织，将神经示踪剂葡聚糖生物素注入大鼠的结状神经节。在示踪剂转运后，对动物进行灌流，并将其幽门和胃窦作为整体标本进行准备。标本经过处理以永久标记示踪剂，并用 Cuprolinic blue 进行亚组染色或免疫染色以检测 c-Kit。环形肌中的肌内丛（IMAs）构成了括约肌的主要迷走传入神经支配。这些幽门环 IMA 分布密集，具有多种结构特化。支配幽门的神经末梢与相邻胃窦环形肌中相应的 IMA 样本之间的形态计量学比较突出表明，括约肌 IMA 大量分支，形成的分支比胃窦 IMA 多两倍以上（分别为 405 个和 165 个），并且将其众多神经突凝聚成紧凑的感受野（约为胃窦 IMA 面积的 48%）深在环形肌中（距黏膜下约 6μm）。括约肌 IMA 丛的单独分支相互交织并重叠，形成围绕幽门管的 360°机械感受器带。迷走神经 IMA 分支的环形带，即紧密插入幽门环的潜在牵张感受器，位于幽门管腔附近，其结构具有基于高灵敏度和精细空间分辨率的幽门感觉图产生肠道反射的潜力。
