骶髓后连合核内躯体初级传入粗纤维的证明及其意义探讨

近 2 0年来的研究表明 ,骶髓后连合核是接受和中继盆腔脏器初级传入信号的重要内脏感觉核团。通过盆神经传入脊髓的盆腔脏器初级传入神经纤维除一部分投射于中间带外侧核区参与排尿反射活动的调控外 ,其余部分基本上都投射于骶髓后连合核。本文作者等又曾发现躯体神经 (坐骨神经、阴部神经 )的初级传入粗纤维有一部分经后索投射于后连合核 ,推测这些躯体初级传入粗纤维可能与内脏传入细纤维汇聚于后连合核神经元并在此进行机能的整合、产生新的神经效应。但是投射于后连合区的躯体初级传入粗纤维 ,必须在电镜下直接证实。为此 ,本研究通过透射电镜及 HRP标记电镜技术探索了阴部神经躯体初级传入粗纤维在后连合核区的存在 ,并用 Philips CM-10 0电镜附件 Measuring装置测量了这种纤维的轴突直径和髓鞘厚度、通过计算求得了它们之间的比例 ( A/M值 ) ,藉此取得了科学地辨认并确证粗纤维的根据

VERIFICATION AND SIGNIFICANCE OF PROJECTION OF SOMATIC PRIMARY THICK MYELINATED FIBERS TO THE SACRAL DORSAL COMMISSURAL NUCLEUS

It has been well established during the past 20 years, that the sacral dorsal commissural nucleus (SDCN) is the major visceral sensory nucleus that receives and transmits the primary afferent signals from the pelvic organs. The visceral primary afferents from the pelvic nerve not only partly project to the sacral parasympathetic nucleus which is involved in micturation, but also mainly project to SDCN. Our previous studies have shown that a considerable number of somatic sciatic and pudendal nerve afferents project to dorsal gray commissure through dorsal funiculus. It was speculated that the somatic primary myelinated fibers and the visceral primary unmyelinated fibers possibly converged onto SDCN neurons to produce new neuronal effect by functional integration. In order to examine whether the somatic primary thick myelinated fibers terminate in SDCN, the pudendal nerve myelinated afferents were investigated by a combination of electron microscope and HRP labeling technique. The myelinated fibers in SDCN were randomly selected and their diameter (A), myelin sheath thickness (M) and the rate of the two parameters (A/M) were counted and measured with the aid of the measuring apparatus of the electron microscope. The results show that the SDCN receives thick myelinated fibers.