中文摘要：

目的 观察大鼠三叉神经节（TG）内的内吗啡肽2（EM2）阳性神经元向延髓背角（MDH）的投射情况。方法 荧光金（FG）追踪与EM2免疫荧光组织化学染色相结合的双标方法。结果 将FG注入MDH后，TG内可见大量FG标记的大、中、小型神经元；TG内也可见各种直径的EM2阳性神经元；TG内的许多FG标记神经元呈EM2阳性，FG／EM2双标神经元多为中、小型神经元。结论 TG内的EM2阳性神经元向MDH投射。

英文摘要：

Objective To observe whether endomorphin-2-immunoreactive （EM2-ir） neurons in the trigeminal ganglion （TG） project to the medullary dorsal horn （MDH） in the rat. Methods Fluoro-gold （FG） retrograde tracing and immunofluorescent histochemical staining for EM2 were applied. Results After FG was injected into the MDH, many FG labeled neurons with small, medium and large diameters were observed in the TG. There were also aboundant EM2-ir neurons with different diameters in the TG. The majority of FG labeled neurons in the TG showed EM2-immunoreactivities. Almost all of the EM2/FG double-labeled neurons were medium and small in size. Conclusion EM2-ir neurons in the TG project to the MDH in the rat.