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将结合生物素的葡聚糖胺 (BDA)注射到大鼠腰骶髓后 ,在电镜下观察脑桥Barrington核内腰骶髓投射神经元与来自腰骶髓传入投射纤维间的突触联系。与先前的研究相一致 ,注射BDA到腰 6和骶 1节段后 ,光镜下可见Barrington核内出现大量顺行标记的神经末梢和一定数量的逆行标记细胞。电镜下发现标记的轴突末梢和标记的树突之间存在直接的突触连接。结果表明 ,Barrington核直接接受腰骶髓的传入投射 ,提示大鼠脑桥排尿反射的脊髓内上行投射通路中可能存在一条直接通路。
The biotin-conjugated dextran amine (BDA) was injected into the lumbosacral spinal cord of rats to observe the synaptic connections between the lumbosacral spinal neurons in the Barrington nucleus and the projection fibers from the lumbosacral spinal cord. Consistent with previous studies, a large number of paraffin-embedded nerve terminals and a number of retrogradely labeled cells appeared in the Barrington nucleus under light microscopy after injection of BDA into the lumbosacral and sacral segments. Electron microscopy revealed a direct synaptic connection between the labeled axon tips and the labeled dendrites. The results show that the Barrington nucleus directly receives the afferent projection of the lumbosacral spinal cord, suggesting that there may be a direct pathway in the intrasynaptic up-projection pathway in the rat pontine reflex.