Ghabriel M N, Jennings K H, Allt G
Department of Anatomy and Cell Biology, Charing Cross and Westminster Medical School, London, England.
Anat Embryol (Berl). 1989;180(3):237-42. doi: 10.1007/BF00315882.
While the perineurium as a diffusion barrier has been extensively investigated by light and electron microscopy, such studies have been largely restricted to the use of protein tracers. In the present study the permeability of the perineurium to a physiologically more relevant ionic tracer has been assessed. In vivo the rat sural or tibial nerve was either microinjected with lanthanum nitrate solution for endoneurial application or bathed in the lanthanum solution for epineurial application. The findings generally demonstrated an effective barrier to the tracer which failed to penetrate the inner layers of the perineurium. Only at the highest lanthanum concentration and longest time intervals employed did trace quantities occasionally penetrate the barrier and then only in the presence of some cytopathological changes to the outermost perineurial cells. The usefulness of the microinjection method was limited by the slight but unavoidable trauma to the perineurium. The findings are related to those of other studies which have used electron dense tracers, also to studies using physiological including electrophysiological techniques and morphological including freeze-fracture methods.
虽然通过光学显微镜和电子显微镜对神经束膜作为扩散屏障进行了广泛研究，但此类研究主要局限于使用蛋白质示踪剂。在本研究中，已评估了神经束膜对生理上更相关的离子示踪剂的通透性。在体内，大鼠腓肠神经或胫神经要么被微量注射硝酸镧溶液用于神经内膜给药，要么浸泡在镧溶液中用于神经外膜给药。研究结果总体上表明，示踪剂存在有效的屏障，无法穿透神经束膜的内层。只有在使用最高镧浓度和最长时间间隔时，微量示踪剂才偶尔穿透屏障，而且只有在最外层神经束膜细胞出现一些细胞病理学变化的情况下才会如此。微量注射法的效用受到对神经束膜轻微但不可避免的损伤的限制。这些发现与其他使用电子致密示踪剂的研究结果相关，也与使用生理学方法（包括电生理学技术）和形态学方法（包括冷冻断裂法）的研究相关。
