Stofer W D, Horn J P
Department of Physiology, University of Pittsburgh, School of Medicine, Pennsylvania 15261.
J Neurosci. 1993 Feb;13(2):801-7. doi: 10.1523/JNEUROSCI.13-02-00801.1993.
The relation between birthdates of sympathetic neurons and their subsequent differentiation into cutaneous B cells and vasomotor C cells was examined in paravertebral ganglia 9 and 10 of the bullfrog tadpole. Neurons undergoing terminal cell division were identified by injecting tadpoles repeatedly with 5'-bromodeoxyuridine (BRDU) for one to six developmental stages between III and XXI. After allowing the tadpoles to enter late metamorphic stages (XX-XXV), the ganglia were double immunostained for BRDU and neuropeptide Y (NPY). NPY is a marker for mature C-type neurons (Horn et al., 1987). Double-labeled neurons were readily discerned through use of distinct black and brown HRP reaction products and also because immunoreactivity for BRDU was localized in nuclei while that for NPY was localized in perinuclear cytoplasm. Counts of labeled cells showed that neurogenesis occurs throughout limb bud and paddle stages, and that it ceases during early foot stages (XII-XIV), a time coinciding with the onset of NPY expression. By contrast, the labeling of non-neuronal satellite cells with BRDU was most common weeks later during metamorphic stages. Irrespective of their birthdates, about half of the BRDU-labeled neurons were also positive for NPY immunoreactivity. This proportion of NPY-positive cells is indistinguishable from that in the entire adult ganglia (Horn et al., 1987). In addition to establishing that neurogenesis and gliogenesis occurs during tadpole stages, the results indicate that the onset of NPY expression by vasomotor C neurons is unrelated to their time of origin. In other words, the last wave of neurogenesis in sympathetic ganglia does not give rise to a specific subclass of sympathetic neurons.
在牛蛙蝌蚪的第9和第10椎旁神经节中，研究了交感神经元的出生日期与其随后分化为皮肤B细胞和血管运动C细胞之间的关系。通过在蝌蚪发育的III至XXI阶段的一至六个阶段重复注射5'-溴脱氧尿苷（BRDU）来识别正在进行终末细胞分裂的神经元。在蝌蚪进入晚期变态阶段（XX - XXV）后，对神经节进行BRDU和神经肽Y（NPY）的双重免疫染色。NPY是成熟C型神经元的标志物（Horn等人，1987）。通过使用不同的黑色和棕色HRP反应产物，并且由于BRDU的免疫反应性定位于细胞核中而NPY的免疫反应性定位于核周细胞质中，很容易辨别出双标记神经元。标记细胞的计数表明，神经发生在整个肢芽和桨状阶段都有发生，并且在早期足部阶段（XII - XIV）停止，这一时期与NPY表达的开始时间一致。相比之下，用BRDU标记非神经元卫星细胞在变态阶段数周后最为常见。无论其出生日期如何，约一半的BRDU标记神经元对NPY免疫反应性也呈阳性。NPY阳性细胞的这一比例与整个成年神经节中的比例没有区别（Horn等人，1987）。除了确定在蝌蚪阶段发生神经发生和胶质发生外，结果还表明血管运动C神经元NPY表达的开始与其起源时间无关。换句话说，交感神经节中最后一波神经发生不会产生交感神经元的特定亚类。
