Schalow G, Barth H
Department of Neuropathology, Freie Universität Berlin, Germany.
Gen Physiol Biophys. 1992 Feb;11(1):85-99.
Single action potentials and their conduction times were recorded extracellularly from dog and human lower sacral nerve roots. Conduction velocity frequency distribution histograms were constructed and peaks of single extrafusal and intrafusal motoneuron distributions were identified. The electrophysiologically measured roots were removed and morphometrically analysed. Nerve fibre diameter frequency distribution histograms were constructed with respect to 3 myelin sheath thickness ranges, and peaks of single motoneuron group distributions were identified. The identified motoneuron classes, characterized by their group peak values of conduction velocity at about 36 degrees C and fibre diameter were: dog: intrafusal: gamma 22(23ms-1/4.8 microns),gamma 21(33/5.7), gamma 1 (43/6.7),gamma beta?(54/10.1) extrafusal: alpha 3(61ms-1/11.7 microns),alpha 2(72/13.6), alpha 11 (81/15.2), alpha 12(86/16.8),alpha 13(95/19) human: intrafusal: gamma 21(15ms-1/5.8 microns), gamma 1(20/6.8), gamma beta?(27/7.2) extrafusal: alpha 3(37ms-1/8.3 microns),alpha 2(50/10.2), alpha 1(60/13.1) The 60 (alpha 3) to 30% (alpha 1-motoneurons) higher conduction velocities in dogs as compared to humans seem to originate in the 40 (alpha 3) to 30% (alpha 1-motoneurons) larger nerve fibre diameters. However, the myelin sheath seemed to be 0.1 to 0.2 microns thinner in dogs than in humans. The pair-values "conduction velocity-fibre diameter" of the alpha and gamma-motoneuron groups were lying on different correlation curves in the velocity-diameter plane indicating structural and/or geometrical differences between alpha and gamma-motoneurons.
在狗和人的骶神经下根处，通过细胞外记录的方式记录单动作电位及其传导时间。构建传导速度频率分布直方图，并确定单根梭外肌和梭内肌运动神经元分布的峰值。将通过电生理测量的神经根部移除并进行形态学分析。针对3个髓鞘厚度范围构建神经纤维直径频率分布直方图，并确定单运动神经元组分布的峰值。所确定的运动神经元类别，以其在约36摄氏度时的传导速度组峰值和纤维直径为特征，具体如下：狗：梭内肌：γ22（23毫秒-1/4.8微米），γ21（33/5.7），γ1（43/6.7），γβ？（54/10.1）；梭外肌：α3（61毫秒-1/11.7微米），α2（72/13.6），α11（81/15.2），α12（86/16.8），α13（95/19）。人：梭内肌：γ21（15毫秒-1/5.8微米），γ1（20/6.8），γβ？（27/7.2）；梭外肌：α3（37毫秒-1/8.3微米），α2（50/10.2），α1（60/
