Pannese E, Procacci P, Ledda M, Conte V
Institute of Histology, Embryology and Neurocytology, University of Milan, Italy.
J Neurocytol. 1996 Feb;25(2):137-46. doi: 10.1007/BF02284792.
The volumes of the nerve cell bodies and those of the enveloping satellite cell sheaths from spinal ganglia of young adult and aged rabbits were determined by morphometric methods using the electron microscope. The mean volume of the nerve cell bodies was greater in the old rabbits than in young adults; this is probably related to the larger body size of the old animals. The mean volume of the satellite cell sheaths was, however, smaller in the aged rabbits than in the young adults. Consequently the volume ratio between the satellite cell sheaths and the related nerve cell bodies was significantly smaller in the aged animals. Since satellite cells play an important role in the support of the neuron, the reduction in volume of the perineuronal sheath could be associated with a decrease in the trophic activity of satellite cells towards the enveloped neuron with consequences for neuronal activity. Furthermore, in the satellite cell sheaths of old rabbits, the number and extension of gaps that leave the neuronal surface directly exposed to the basal lamina were significantly increased. Since spinal ganglia lack a blood-nervous tissue barrier, only the satellite cell sheath controls the traffic of material to the nerve cell body. Because the neuronal surface unprotected by the satellite cell envelopment is significantly more extensive in the spinal ganglia of old rabbits than in those of young adults, the nerve cells of the former are more exposed to potential damage by harmful substances. A dense undercoating was seen very frequently beneath the portions of the neuronal plasma membrane not covered by satellite cells.
运用电子显微镜形态测量法，测定了成年幼兔和老年兔脊髓神经节神经细胞体以及包裹它们的卫星细胞鞘的体积。老年兔神经细胞体的平均体积大于成年幼兔，这可能与老年动物体型较大有关。然而，老年兔卫星细胞鞘的平均体积小于成年幼兔。因此，老年动物中卫星细胞鞘与相关神经细胞体的体积比显著更小。由于卫星细胞在神经元支持方面发挥重要作用，神经周鞘体积的减小可能与卫星细胞对被包裹神经元的营养活性降低有关，进而影响神经元活性。此外，在老年兔的卫星细胞鞘中，使神经元表面直接暴露于基膜的间隙数量和范围显著增加。由于脊髓神经节缺乏血神经组织屏障，只有卫星细胞鞘控制物质向神经细胞体的运输。因为在老年兔脊髓神经节中，未被卫星细胞包裹的神经元表面比成年幼兔的更广泛地暴露在外，所以老年兔的神经细胞更容易受到有害物质的潜在损伤。在未被卫星细胞覆盖的神经元质膜部分下方，经常可见一层致密的底层。
