Hulsebosch C E, Coggeshall R E
Brain Res. 1983 Dec 12;288(1-2):77-83. doi: 10.1016/0006-8993(83)90082-3.
To test for sprouting of dorsal root axons, 3 consecutive dorsal roots were sectioned above and 3 were sectioned below a spared root in rats 1 month and 24 months old. At various survival times, myelinated and unmyelinated axons were counted in the spared root, the first cranial root and the first caudal root, and these counts were compared to similar counts from the same roots on the unoperated side. The counts of myelinated axons in all roots and of unmyelinated axons in the caudal roots were not different from the counts in the same roots on the unoperated side. Thus there is no evidence for sprouting of these axons in our system. By contrast, the unmyelinated axons in the cranial and spared roots were significantly increased as compared to the unmyelinated axons in the same roots on the unoperated side. We interpret this increase to be sprouting of dorsal root axons. To determine the effects of age, animals operated at 1 month and sacrificed 1 month, 3 months or 18 months later were compared with animals operated at 2 years and sacrificed 1 month later. The unmyelinated axons were greater by approximately 20% on the operated side in the cranial and spared roots in the young rats and by approximately 8% in old rats. Thus the sprouting of unmyelinated axons is more vigorous when the surgery is performed in young animals, but there still seems to be a response in older animals.
为检测背根轴突的发芽情况，在1月龄和24月龄大鼠的一条保留神经根上方切断3条连续的背根，在其下方也切断3条连续的背根。在不同的存活时间，对保留神经根、第一对脑神经根和第一对尾神经根中的有髓和无髓轴突进行计数，并将这些计数结果与未手术侧相同神经根的类似计数结果进行比较。所有神经根中有髓轴突的计数以及尾神经根中无髓轴突的计数与未手术侧相同神经根的计数没有差异。因此，在我们的系统中没有证据表明这些轴突会发芽。相比之下，与未手术侧相同神经根中的无髓轴突相比，脑神经根和保留神经根中的无髓轴突显著增加。我们将这种增加解释为背根轴突的发芽。为确定年龄的影响，将1月龄时手术并在1个月、3个月或18个月后处死的动物与2岁时手术并在1个月后处死的动物进行比较。幼鼠手术侧脑神经根和保留神经根中的无髓轴突比未手术侧大约多20%，老龄大鼠则大约多8%。因此，在幼龄动物中进行手术时，无髓轴突的发芽更为活跃，但老龄动物似乎也仍有反应。
