Kiernan J A
Med Hypotheses. 1978 Jan-Feb;4(1):15-26. doi: 10.1016/0306-9877(78)90022-1.
Nerve fibres severed within peripheral nerves are able to regenerate and reinnervate the structures they formerly supplied. Most axons severed within the mammalian central nervous system (CNS) do not regenerate in this way. Regenerative axonal growth begins to occur in the CNS but ceases about two weeks after injury. Five earlier theories purporting to explain this difference are reviewed and found not to account satisfactorily for many experimental observations. A new hypothesis is advanced in which it is held that in order for regeneration to take place, the growing tips of the axons must be surrounded by extracellular fluid containing proteins (of specified identity) derived from the blood plasma. Such proteins are thought to be imbibed by the tips of the fibres and transported retrogradely to the neuronal cell-bodies. With this hypothesis it is possible to explain the success of axonal regeneration in peripheral nerves and its failure in the CNS. It is also possible to account for the exceptional circumstances in which axons do regenerate in the CNS. Various experiments are suggested for testing the validity of the new hypothesis.
外周神经内被切断的神经纤维能够再生，并重新支配它们之前所供应的结构。大多数在哺乳动物中枢神经系统（CNS）内被切断的轴突不会以这种方式再生。再生性轴突生长在中枢神经系统中开始出现，但在损伤后约两周停止。本文回顾了五种早期试图解释这种差异的理论，发现它们不能令人满意地解释许多实验观察结果。本文提出了一个新的假说，即认为为了实现再生，轴突的生长尖端必须被含有源自血浆的蛋白质（具有特定特性）的细胞外液所包围。这些蛋白质被认为会被纤维尖端吸收，并逆向运输到神经元细胞体。基于这个假说，可以解释外周神经中轴突再生的成功以及中枢神经系统中轴突再生的失败。也能够解释轴突在中枢神经系统中确实再生的特殊情况。本文还提出了各种实验来检验新假说的有效性。
