McLean J H, Hopkins D A
J Comp Neurol. 1982 Apr 10;206(3):243-52. doi: 10.1002/cne.902060304.
The efferent connections of two types neurons in the dorsal motor nucleus of the vagus nerve (DMV) were studied in the cat by light and electron microscopy following horseradish peroxidase (HRP) injections into the cervical vagus nerve or brainstem. After injections of HRP into the vagus nerve, up to 80% of medium-sized neurons averaging 26 x 20 micrometers in 1-micrometer-thick sections were retrogradely labeled while no small neurons were labeled in the DMV. Incubation with either diaminobenzidene (DAB) or p-phenylenediamine-pyrocatechol (PPD-PC) chromogens yielded electron-dense reaction products localized mainly in lysosomes. Identification of label at the ultrastructural level was facilitated by omitting lead citrate staining and by counting numbers of lysosomes, which were higher in labeled neurons. Quantitative comparisons of the dimensions of labeled and unlabeled somata demonstrated that retrograde transport and incorporation of HRP had no effect on cell size within the 2-3-day survival times used in this study. In order to determine whether neurons in the DMV project to higher levels of the brain stem, large injections of HRP (1-3 microliters) were made into the pons, mesencephalon, hypothalamus, and amygdala. After injections of HRP into the brainstem, only small neurons, measuring 17 x 10 micrometers, were retrogradely labeled. Approximately 90% of the small neurons remained unlabeled following the HRP injections. The ultrastructural features of the labeled small neurons included an invaginated nucleus, low cytoplasmic/nuclear ratio, and relatively fewer organelles than the medium-sized neurons. A quantitative analysis of labeled and unlabeled small neurons demonstrated that the labeled neurons were significantly larger than the unlabeled small neurons. Thus, two populations of small neurons may exist in the DMV. One population appears to have ascending projections to higher levels of the brainstem while the other more numerous population may be interneurons or project for only short distances.
通过将辣根过氧化物酶（HRP）注入猫的颈迷走神经或脑干，利用光镜和电镜研究了迷走神经背运动核（DMV）中两类神经元的传出连接。将HRP注入迷走神经后，在1微米厚的切片中，平均直径为26×20微米的中型神经元中有高达80%被逆行标记，而DMV中的小型神经元未被标记。用二氨基联苯胺（DAB）或对苯二胺 - 邻苯二酚（PPD - PC）显色剂孵育后，电子致密反应产物主要定位于溶酶体。通过省略柠檬酸铅染色和计数溶酶体数量，有助于在超微结构水平上识别标记，标记神经元中的溶酶体数量更多。对标记和未标记的胞体尺寸进行定量比较表明，在本研究使用的2 - 3天存活期内，HRP的逆行运输和掺入对细胞大小没有影响。为了确定DMV中的神经元是否投射到脑干的更高水平，将大量HRP（1 - 3微升）注入脑桥、中脑、下丘脑和杏仁核。将HRP注入脑干后，只有直径为17×10微米的小型神经元被逆行标记。HRP注射后，约90%的小型神经元未被标记。标记的小型神经元的超微结构特征包括核内陷、低细胞质/核比率以及与中型神经元相比相对较少的细胞器。对标记和未标记的小型神经元进行定量分析表明，标记的神经元明显大于未标记的小型神经元。因此，DMV中可能存在两类小型神经元。一类似乎向脑干的更高水平有上行投射，而另一类数量更多的群体可能是中间神经元或仅投射较短距离。
