Jakeman L B, Reier P J, Bregman B S, Wade E B, Dailey M, Kastner R J, Himes B T, Tessler A
Department of Neurological Surgery, University of Florida, College of Medicine, Gainesville 32610.
Exp Neurol. 1989 Jan;103(1):17-33. doi: 10.1016/0014-4886(89)90181-7.
The differentiation of intracerebral and intraspinal transplants of fetal (E14-E15) rat spinal cord was studied to determine the extent to which myelin-free zones in these embryonic grafts exhibit cytological features and immunocytochemical characteristics of the substantia gelatinosa (SG) of the normal spinal cord. Immunocytochemical staining with antiserum to myelin basic protein (MBP) revealed myelin-free areas of varying proportions within fetal spinal cord grafts. These regions were identified in both newborn and adult recipients regardless of whether donor tissue was grafted to heterotopic (intracerebral) or homotopic (intraspinal) sites. As in the SG of the intact spinal cord, the myelin-free regions consisted mainly of small (7-15 microns) diameter neurons. At the ultrastructural level, these cells were surrounded by a neuropil composed of numerous small caliber, unmyelinated axons and intermediate-sized dendrites. Synaptic terminals in these areas were primarily characterized by the presence of clear, round vesicles, although granular vesicles were occasionally found within these terminals. Immunocytochemical staining demonstrated met- and leu-enkephalin-, neurotensin-, substance P-, and somatostatin-like immunoreactive elements within these myelin-free areas. Thus, regions within embryonic spinal cord grafts undergo some topographical differentiation which parallels that of the normal superficial dorsal horn. The presence of SG-like regions illustrates the potential capacity of fetal spinal cord transplants for replacing some intraspinal neuronal populations at the site of a spinal cord injury in neonatal and adult animals. These graft regions may serve as a source of intersegmental projection neurons or establish an extensive intrinsic circuitry similar to that seen in the normal SG. In addition, the definition of these areas provides a useful model to study the innervation patterns of host axons that typically project to the substantia gelatinosa of the normal spinal cord.
研究了胎鼠（E14 - E15）脊髓脑内和脊髓内移植后的分化情况，以确定这些胚胎移植物中的无髓鞘区在多大程度上表现出正常脊髓胶状质（SG）的细胞学特征和免疫细胞化学特性。用抗髓鞘碱性蛋白（MBP）抗血清进行免疫细胞化学染色，显示胎鼠脊髓移植物内有无髓鞘区，比例各异。无论供体组织移植到异位（脑内）还是同位（脊髓内）部位，在新生和成年受体中均能识别出这些区域。与完整脊髓的SG一样，无髓鞘区主要由直径较小（7 - 15微米）的神经元组成。在超微结构水平上，这些细胞被由许多小口径无髓鞘轴突和中等大小树突组成的神经毡所包围。这些区域的突触终末主要特征是存在清亮的圆形囊泡，尽管偶尔也能在这些终末内发现颗粒囊泡。免疫细胞化学染色显示这些无髓鞘区内存在甲硫氨酸脑啡肽和亮氨酸脑啡肽、神经降压素、P物质和生长抑素样免疫反应性成分。因此，胚胎脊髓移植物内的区域经历了一些与正常浅表背角平行的拓扑分化。SG样区域的存在说明了胎鼠脊髓移植在新生和成年动物脊髓损伤部位替代一些脊髓内神经元群体的潜在能力。这些移植区域可能作为节段间投射神经元的来源，或建立类似于正常SG中所见的广泛内在神经回路。此外，这些区域的界定为研究通常投射到正常脊髓胶状质的宿主轴突的神经支配模式提供了一个有用的模型。
