大鼠Barrington核内脊髓投射神经元直接接受腰骶髓传入的电镜研究

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。

Direct projection from the lumbosacral spinal cord to spinally- projecting neurons in Barrington''s nucleus: an electron microscopic study in the rat

An electron microscopic experiment was performed to examine if spinally projecting neurons in Barrington's nucleus receive direct projection from the lumbosacral spinal cord following injection of biotinylated dextran amine (BDA) into the lumbosacral spinal cord in the rat. Consistent with previous study, at light microscopic level, numerous anterogradely labeled axon terminals and some retrogradely labeled cell bodies were seen in Barrington's nucleus after injection of BDA into the lumbosacral spinal cord. Electron microscopic observations showed that some BDA labeled axon terminals made synaptic contact with dendrites labeled with BDA. The present results indicate that Barrington's nucleus receives direct afferents from the lumbosacral spinal cord, and suggest that there may be a direct ascending pathway from the lumbosacral spinal cord to Barrington's nucleus in the pontine micurition reflex of the rat. [