Immuno-electron microscopic alalysis of brain photoreceptor in birds.

已有报道在禽脑外侧隔区存在血管活性肠肽(VIP)和促性腺激素释放激素(GnRH)神经元。在侧脑室邻近的外侧隔器内侧部(LSOm)发现VIP样免疫反应(Ir)神经元的聚集，其中许多神经元表现出接触脑脊液神经元的特征。近年来，这种类型的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深层。在本研究中，我们使用光(LM)和电子显微镜(EM)水平的双重标记技术来研究VIP和GnRH-ir神经元是否在鸽子的外侧隔区进行通信。在光镜下可见VIP-ir神经元与GnRH-ir神经元紧密联系，部分VIP-ir纤维分布于GnRH-ir胞体附近。对这些神经元的EM观察表明，VIP-ir轴突终末与GnRH-ir神经元的核膜和树突有突触接触。这些结果表明，VIP神经元与GnRH神经元在鸽子外侧隔内可直接通信，该区域可能在繁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.