Pompolo S, Furness J B
Department of Anatomy and Cell Biology, University of Melbourne, Parkville, Australia.
J Neurocytol. 1993 Jul;22(7):531-46. doi: 10.1007/BF01189041.
Calretinin immunoreactivity is almost completely confined to two classes of neuron in the myenteric plexus of the guinea-pig small intestine, longitudinal muscle motor neurons and ascending interneurons. Nerve cell bodies of the two classes can be readily identified by their sizes and positions in ganglia. The motor neurons, which are small Dogiel type I neurons, are about 20% and the interneurons, which are medium-sized Dogiel type I neurons, are about 5% of myenteric neurons. In the present work, we have also discovered a minor population (0.1%) of small filamentous neurons. In unoperated regions of intestine, at the light microscopic level, numerous calretinin immunoreactive nerve fibres were found in the tertiary plexus that innervates the longitudinal muscle and a medium density of varicose fibres formed pericellular endings in the myenteric ganglia. After double myotomy operations, in areas of plexus 0.5 to 1.5 mm wide which were isolated from ascending and descending inputs, calretinin-immunoreactive fibres of the tertiary plexus were unchanged, but the pericellular endings in the ganglia disappeared. Both the ascending interneurons and the longitudinal muscle motor neurons received ultrastructurally identified synapses and close axonal contacts that were calretinin-immunoreactive. These were counted in semi-serial sections from normal intestine and from regions between myotomy operations. In unoperated intestine, the proportions of calretinin-immunoreactive synapses on small, calretinin-immunoreactive, Dogiel type I nerve cells and small filamentous nerve cells were 30% and 0.1% respectively and on medium-sized Dogiel type I cells the proportion was 28%. Electron microscopy revealed an almost complete loss of immunoreactive inputs to the small Dogiel type I cells between double myotomies, but the number of unreactive inputs was the same as in normal intestine. This work demonstrates that the ascending calretinin-immunoreactive interneurons connect with one another to form ascending chains in the myenteric plexus and that they also provide about 1/3 of the inputs received by calretinin-immunoreactive longitudinal muscle motor neurons. Many of the remaining inputs to these motor neurons are local; we have deduced that these are mainly from primary sensory neurons.
钙视网膜蛋白免疫反应几乎完全局限于豚鼠小肠肌间神经丛中的两类神经元，即纵肌运动神经元和升支中间神经元。这两类神经细胞体可通过其在神经节中的大小和位置轻易识别。运动神经元是小型的多吉尔I型神经元，约占肌间神经节神经元的20%，而中间神经元是中型的多吉尔I型神经元，约占5%。在本研究中，我们还发现了一小部分（0.1%）小型丝状神经元。在未手术的肠段，在光学显微镜下，在支配纵肌的三级神经丛中发现了大量钙视网膜蛋白免疫反应性神经纤维，并且中等密度的曲张纤维在肌间神经节中形成了细胞周围终末。在进行双侧肌切开术后，在与升支和降支输入隔离的0.5至1.5毫米宽的神经丛区域，三级神经丛的钙视网膜蛋白免疫反应性纤维未发生变化，但神经节中的细胞周围终末消失了。升支中间神经元和纵肌运动神经元都接受了超微结构鉴定的、钙视网膜蛋白免疫反应性的突触和紧密轴突接触。这些在来自正常肠段和肌切开术之间区域的半连续切片中进行计数。在未手术的肠段，小型的、钙视网膜蛋白免疫反应性的多吉尔I型神经细胞和小型丝状神经细胞上钙视网膜蛋白免疫反应性突触的比例分别为30%和0.1%，在中型多吉尔I型细胞上的比例为28%。电子显微镜显示，在双侧肌切开术之间，小型多吉尔I型细胞上的免疫反应性输入几乎完全丧失，但无反应性输入的数量与正常肠段相同。这项研究表明，升支钙视网膜蛋白免疫反应性中间神经元在肌间神经丛中相互连接形成升支链，并且它们还提供了钙视网膜蛋白免疫反应性纵肌运动神经元所接收输入的约1/3。这些运动神经元的许多其余输入是局部性的；我们推断这些主要来自初级感觉神经元。
