Immuno-electron microscopic alalysis of brain photoreceptor in birds.

在鸟类大脑的外侧隔膜中，存在血管活性肠多肽（VIP）和含有促性腺激素释放激素（GnRH）的神经元。侧脑室旁侧隔器官内侧部（pars medialis of lateral septal organ, LSOm）内可见vip样免疫反应性（ir）神经元的聚集，其中许多神经元表现出与csf接触神经元的特征。近年来，这类神经元被认为是鸟类脑深部光感受器的候选神经元。GnRH-ir神经元位于LSOm的较深层。在本研究中，我们在光镜（LM）和电镜（EM）水平上使用双标记技术来研究vip -和GnRH-ir神经元是否在鸽子的外侧隔膜中进行通信。在LM水平，VIP-ir神经元与GnRH-ir神经元紧密结合，部分VIP-ir纤维在GnRH-ir细胞体附近运行。EM检查显示VIP-ir轴突末端与GnRH-ir神经元核周和树突有突触状接触。这些结果表明，VIP神经元可以直接与鸽子外侧隔膜的GnRH神经元交流，该区域可能在生殖现象中起重要作用。

In the lateral septum of the avian brain, the presence of vasoactive intestinal polypeptide (VIP) -and gonadotrophin releasing hormone (GnRH) -containing neurons has been reported. An accumulation of VIP-like immunoreactive (ir) neurons is found in the area adjacent to the lateral ventricles which is called pars medialis of lateral septal organ (LSOm) and many of them displayd the characteristic features of CSF-contacting neurons. Recently, this type of neuron is considered as a candidate of deep brain photoreceptor in birds. GnRH-ir neurons are located in the deeper layr of LSOm. In the present study, we used double-labeling techniques at the light (LM) and electron-microscopic (EM) levels to investigate whether VIP-and GnRH-ir neurons communicate in the lateral septum of the pigeon. At the LM levels, VIP-ir neurons and GnRH-ir neurons were seen in close association and some VIP-ir fibers ran near GnRH-ir cell bodies. Examination of these neurons at the EM revealed that VIP-ir axon terminals had synaptoid contacts with perikarya and dendrite of GnRH-ir neurons. These results suggest that VIP neurons could communicate directly with GnRH neurons in the lateral septum of the pigeon and this area might play an important role for reproductive phenomena.