BACKGROUND There is a unique nucleus (CSF-contacting nucleus) in the brain of rat. It has been demonstrated in our previous research. The extraordinary feature of this nucleus is that it is not connected to any parenchymal organ but to the CSF. In primates, however, the presence or absence of this nucleus has not been proven. Confirmation of the presence of this nucleus in primates will provide the structural basis for brain-CSF communication and help to understand the neurohumoral regulatory mechanisms in humans. METHODS The tracer cholera toxin B subunit conjugated to horseradish peroxidase (CB-HRP) was injected into the CSF in the lateral ventricle (LV) of primate rhesus monkeys. After 48 h, the monkeys were perfused and the brain was dissected out, and sectioned for CB-HRP staining. The CB-HRP positive structures were observed under confocal and electron microscopy. The three-dimensional (3D) structure of the CB-HRP positive neurons cluster was reconstructed by computer software. RESULTS (1) CB-HRP labeling is confined within the ventricle, but not leakage into the brain parenchyma. (2) From the midbrain inferior colliculus superior border plane ventral to the aqueduct to the upper part of the fourth ventricle (4V) floor, a large number of CB-HRP positive neurons are consistently located, form a cluster, and are symmetrically located on both sides of the midline. (3) 3D reconstruction shows that the CB-HRP positive neurons cluster in the monkey brain occupies certain space. The rostral part is large and caudal part is thin appearing a "rivet"-like shape. (4) Under electron microscopy, the CB-HRP positive neurons show different types of synaptic connections with the non-CSF-contacting structures in the brain. Some of the processes stretch directly into the ventricle cavity. CONCLUSION Same as we did in rats, the CSF-contacting nucleus is also existed in the primate brain parenchyma. We also recommend listing it as the XIII pair of cranial nucleus, which is specialized in the communications between the brain and the CSF. It is significant to the completing of innervation in the organism.

中文翻译：

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灵长类动物的一种特殊颅核（脑脊液接触核）。

背景技术大鼠脑中有一个独特的细胞核（CSF-contacting nucleus）。我们之前的研究已经证明了这一点。这个核的非凡特征是它不与任何实质器官相连，而是与脑脊液相连。然而，在灵长类动物中，这种细胞核的存在与否尚未得到证实。确认灵长类动物中存在这种细胞核将为脑-CSF 交流提供结构基础，并有助于了解人类的神经体液调节机制。方法 将与辣根过氧化物酶 (CB-HRP) 结合的示踪霍乱毒素 B 亚基注射到灵长类恒河猴侧脑室 (LV) 的脑脊液中。48小时后，对猴子进行灌注并解剖出大脑，并切片用于CB-HRP染色。在共聚焦和电子显微镜下观察到 CB-HRP 阳性结构。CB-HRP阳性神经元簇的三维（3D）结构通过计算机软件重建。结果 (1) CB-HRP 标记被限制在脑室内，但没有渗入脑实质。(2)从中脑下丘上界平面腹侧至导水管至第四脑室(4V)底板上部，大量CB-HRP阳性神经元一致分布，形成簇状，对称分布于中线两侧。(3) 3D重建显示猴脑中CB-HRP阳性神经元簇占据一定空间。头端大，尾端薄，呈“铆钉”状。(4)在电子显微镜下，CB-HRP 阳性神经元与大脑中的非 CSF 接触结构显示出不同类型的突触连接。一些过程直接延伸到心室腔。结论与我们在大鼠中所做的一样，在灵长类动物脑实质中也存在与CSF接触的核。我们还建议将其列为第 XIII 对颅核，专门用于大脑和 CSF 之间的通信。它对机体神经支配的完成具有重要意义。它专门研究大脑和脑脊液之间的通信。它对机体神经支配的完成具有重要意义。它专门研究大脑和脑脊液之间的通信。它对机体神经支配的完成具有重要意义。