Johnson B M, Sadun A A
Department of Ophthalmology, U.S.C. School of Medicine, Los Angeles 90033.
J Electron Microsc Tech. 1988 Feb;8(2):179-83. doi: 10.1002/jemt.1060080204.
It is a widely held belief that the products of axonal degeneration in the CNS are transitory and are caused by metabolic and phagocytic processes. However, recent light microscopic examinations of human and primate brains using the paraphenylene diamine staining method (PPD), which stains degenerating axons, have confirmed that the products of degeneration persist for years in visual pathways. The routine utilization of the PPD method for delineating human visual pathways requires further confirmation of axonal degeneration. Optic nerves, optic tracts, and lateral geniculate nuclei were collected from human brains that had clinical documentation of optic nerve damage prior to death. Optic nerves, optic tracts, and lateral geniculate nuclei taken from the brains of cynomolgus monkeys that had undergone enucleation 3 months to 1 year prior to sacrifice were also examined. All tissue was processed for electron microscopy; ultrathin sections were cut for electron microscopy, and consecutive sections were cut for light microscopy. In all cases, the homology of the degenerated processes was confirmed between the light microscopic (PPD) and the electron microscopic sections. Such ultrastructural examination demonstrates that the products of axonal degeneration remain in the primate visual system longer than previously supposed.
人们普遍认为，中枢神经系统中轴突退化的产物是短暂的，是由代谢和吞噬过程引起的。然而，最近使用对苯二胺染色法（PPD）对人类和灵长类动物大脑进行的光学显微镜检查证实，退化产物在视觉通路中会持续数年，PPD方法可对退化的轴突进行染色。常规使用PPD方法来描绘人类视觉通路需要进一步证实轴突退化情况。从生前有视神经损伤临床记录的人类大脑中收集视神经、视束和外侧膝状体核。还检查了在处死前3个月至1年进行眼球摘除的食蟹猴大脑中的视神经、视束和外侧膝状体核。所有组织均进行电子显微镜处理；切取超薄切片用于电子显微镜检查，并切取连续切片用于光学显微镜检查。在所有病例中，光学显微镜（PPD）切片和电子显微镜切片之间的退化过程同源性均得到证实。这种超微结构检查表明，轴突退化的产物在灵长类视觉系统中停留的时间比以前认为的更长。
