The dorsal portion of the descending octaval nucleus (dDO), the main first-order auditory nucleus in jawed fish, includes four lateral and three medial neuronal populations that project to the auditory midbrain. One medial population and one lateral population contain neurons that receive a remarkably large axon terminal from the utricular branch of the octaval nerve. Immunocytochemistry for connexin 35 (Cx35) was used to determine whether this connection includes electrical synapses. Although Cx35 was not localized to these large contacts, it was observed in the three other lateral dDO populations. Another first-order nucleus, the dorsal portion of the anterior octaval nucleus (dAO), primitively projects to the auditory midbrain in jawed fishes and contains neurons positive for Cx35. Utricular branch terminals were coincident with some Cx35 puncta in dDO and dAO. The results are discussed in light of what is known about the occurrence of electrical synapses in first-order auditory and vestibular nuclei in fish and tetrapods.

中文翻译：

---

金鱼，鱼背下降和背八角前核中电突触的免疫细胞化学证据。

八爪鱼降级八角形核（dDO）的背侧部分是fish鱼的主要一阶听觉核，包括四个向听觉中脑突出的外侧和三个内侧神经元种群。一个内侧种群和一个外侧种群包含神经元，这些神经元从八叉神经的脑室分支接收非常大的轴突末端。连接蛋白35（Cx35）的免疫细胞化学用于确定该连接是否包括电突触。尽管Cx35并不局限于这些大型接触，但在其他三个侧面dDO群体中也观察到了。另一个一阶核，即八齿形前核（dAO）的背侧部分，最初伸入颚状鱼类的听觉中脑，并包含Cx35阳性的神经元。尿道分支末端与dDO和dAO中的一些Cx35突点重合。根据已知的关于鱼类和四足动物的一级听觉和前庭核中电突触的发生情况对结果进行了讨论。