Kristt D A
Department of Pathology, University of Maryland Medical Center, Baltimore 21201.
J Neuropathol Exp Neurol. 1987 Nov;46(6):668-81.
The purpose of this study was to document in vivo neuronal sprouting in response to local trauma of the mature cerebral neocortex. The experimental approach enabled direct and unequivocal ultrastructural identification of newly sprouted neuronal processes and their synaptic relationships. Morphologically detectable factors that influence neuronal sprouting were also assessed. Tiny fragments of porous, synthetic membrane were implanted into the mature neocortex of the rat. After one week, axons, dendrites, growth cone-like structures, synapses, and processes from astrocytes and microglia were present deep within the interstices of the implant. Morphometric analysis of synapses within the implant, support the qualitative impression of active neuronal ingrowth and de novo synaptogenesis by these sprouted elements. Astrocytic processes appear to comprise the major barrier to neuronal invasion of the implant. Several observations suggested that glia sometimes may facilitate neuronal ingrowth. These findings provide direct morphological documentation of axonal and dendritic plasticity in the mature rat neocortex. The work demonstrates a strategy that could be useful for further evaluating the cellular mechanism of in vivo neuronal regeneration.
本研究的目的是记录成熟大脑新皮质局部创伤后体内神经元的发芽情况。该实验方法能够直接且明确地对新发芽的神经元突起及其突触关系进行超微结构鉴定。还评估了影响神经元发芽的形态学可检测因素。将多孔合成膜的微小碎片植入大鼠成熟的新皮质中。一周后，轴突、树突、生长锥样结构、突触以及星形胶质细胞和小胶质细胞的突起出现在植入物间隙的深处。对植入物内突触的形态计量分析支持了这些发芽元件活跃的神经元向内生长和新生突触形成的定性印象。星形胶质细胞突起似乎构成了神经元侵入植入物的主要障碍。一些观察结果表明，神经胶质有时可能促进神经元向内生长。这些发现提供了成熟大鼠新皮质中轴突和树突可塑性的直接形态学记录。这项工作展示了一种策略，可用于进一步评估体内神经元再生的细胞机制。
