Cameron W E, Fang H
Department of Neurobiology, University of Pittsburgh, PA.
Brain Res Dev Brain Res. 1989 Oct 1;49(2):253-63. doi: 10.1016/0165-3806(89)90026-6.
The morphology of medial gastrocnemius (MG) motoneurons labeled by retrograde transport of horseradish peroxidase was quantified in 5 postnatal ages (3 to 79-86 days) and in adults. A bimodal distribution of somal volumes was evident at birth which permitted separating the motoneurons into alpha and gamma subpopulations for analysis. There was a significant increase in the axial dimensions, surface area and volume calculated for both alpha and gamma cell bodies between each of the age-groups studied. A greater relative growth of the major over minor axis for the gammas produced a significant decrease in the form factor (i.e. greater eccentricity) between the youngest and oldest age-groups. The number of primary dendrites observed remained constant throughout postnatal development. The surface area of alpha somata more than tripled while that of the gammas doubled from 3 days to the adult. The mean somal volume of an alpha motoneuron at birth was only 17% of its adult value while the gamma cell bodies were 33% of their adult volume. A positive correlation was found for both alpha and gamma motoneurons when their somal surface area was plotted against postnatal age and weight. The rate of growth of the MG somal surface area is compared to the changes found in axonal conduction velocity and axonal diameter for MG in the literature.
采用辣根过氧化物酶逆行运输标记法，对5个出生后年龄段（3至79 - 86天）以及成年期的腓肠肌内侧头（MG）运动神经元的形态进行了量化分析。出生时，神经元胞体体积呈现双峰分布，据此可将运动神经元分为α和γ亚群进行分析。在所研究的各年龄组之间，α和γ细胞体的轴向尺寸、表面积和体积均有显著增加。γ细胞体的长轴相对于短轴有更大的相对生长，导致最年幼和最年长年龄组之间的形态因子显著降低（即偏心率增大）。在出生后的整个发育过程中，观察到的初级树突数量保持恒定。从3天到成年期，α细胞体的表面积增加了两倍多，而γ细胞体的表面积增加了一倍。出生时，α运动神经元的平均胞体体积仅为其成年值的17%，而γ细胞体则为其成年体积的33%。当将α和γ运动神经元的胞体表面积与出生后年龄和体重进行绘图时，发现两者呈正相关。本文将MG胞体表面积的生长速率与文献中MG轴突传导速度和轴突直径的变化进行了比较。
