Martinelli C, Sartori P, De Palo S, Ledda M, Pannese E
Institute of Histology, Embryology and Neurocytology, University of Milan, Via Mangiagalli 14, 20133 Milan, Italy.
Anat Embryol (Berl). 2006 Oct;211(5):455-63. doi: 10.1007/s00429-006-0097-x. Epub 2006 Jun 23.
The volumes of the nerve cell bodies and those of the enveloping satellite cell sheaths from spinal ganglia were determined by morphometric methods applied to electron micrographs in young, adult, old and very old rabbits. The mean volume of the nerve cell bodies increased progressively with age; this is probably related to the increase with age of the body size of the rabbits studied. The mean volume of the satellite cell sheaths did not differ significantly in young, adult and old animals, but was significantly smaller in very old animals. It is extremely unlikely that this marked reduction in the volume of the satellite cell sheath is the result of a pathological process. The mean value of the volume ratio between the satellite cell sheaths and the related nerve cell bodies did not differ significantly in young and adult animals, but was significantly smaller in old and very old animals. This ratio was particularly low in very old animals. Our analysis showed that in each age group the volume of the satellite cell sheath is linearly related to the volume of the related nerve cell body. This result suggests that in rabbit spinal ganglia the quantitative relations between glial and nervous tissue are tightly controlled throughout life. It is suggested that ganglionic neurons release signals to influence and control the volume of their associated glial tissue. Since satellite cells have important support roles for the neurons they surround, it is likely that the marked reduction in the volume of perineuronal sheaths in the extremely advanced age is accompanied by a reduction of those roles, with negative consequences for neuronal activity.
运用形态测量方法，对幼年、成年、老年和高龄家兔脊髓神经节的神经细胞体及其周围卫星细胞鞘的体积进行了测定。神经细胞体的平均体积随年龄增长而逐渐增加；这可能与所研究家兔体型随年龄增长有关。卫星细胞鞘的平均体积在幼年、成年和老年动物中无显著差异，但在高龄动物中显著减小。卫星细胞鞘体积的这种显著减小极不可能是病理过程的结果。卫星细胞鞘与相关神经细胞体之间的体积比平均值在幼年和成年动物中无显著差异，但在老年和高龄动物中显著减小。在高龄动物中，这个比值特别低。我们的分析表明，在每个年龄组中，卫星细胞鞘的体积与相关神经细胞体的体积呈线性相关。这一结果表明，在兔脊髓神经节中，神经胶质组织与神经组织之间的数量关系在整个生命过程中受到严格控制。有人提出，神经节神经元释放信号以影响和控制其相关神经胶质组织的体积。由于卫星细胞对它们所包围的神经元具有重要的支持作用，因此在极高龄时神经周鞘体积的显著减小可能伴随着这些作用的减弱，从而对神经元活动产生负面影响。
