Vincent S L, Peters A, Tigges J
Department of Anatomy, Boston University School of Medicine, Massachusetts 02118.
Anat Rec. 1989 Mar;223(3):329-41. doi: 10.1002/ar.1092230312.
A light and electron microscopic examination of area 17 of the visual cortex in well-fixed young (5-6 years) and old (25-35 years) rhesus monkeys was carried out to determine the effects of age on neurons. The analyses were made in a portion of area 17 on the lateral surface of the hemisphere just caudal to the lunate sulcus. Light microscopic measurements of the mean cortical depth in vertically oriented 1-micron-thick sections reveal no obvious thinning with age, and the mean diameters of neuronal nuclei do not change with age. On the basis of counts of neuronal profiles containing nuclei in 250-microns-wide strips of 1-micron-thick sections passing through the entire depth of the cortex, no significant neuronal loss could be detected. These findings are consistent with our electron microscopic observations on this area of the cortex, for in the old monkeys the neurons show little cytological evidence of advanced age beyond the presence of a few lipofuscin granules, although the neuropil contains some profiles of degenerating small-caliber dendrites, myelinated axons, and a few axon terminals. Large vacuoles, some 10 microns or more in diameter, are present in the neuropil of the old animals. Some of these vacuoles appear to represent a late stage in the degeneration of myelinated axons, for they are bounded by a thin, laminated sheath. Other large vacuoles, of unknown origin, often contain membranous debris and have an attenuated limiting membrane. It is concluded that the cell bodies of neurons in area 17 of old rhesus monkeys do not show significant structural changes due to age, although some of the neuronal processes in the neuropil are affected.
对固定良好的幼年（5 - 6岁）和老年（25 - 35岁）恒河猴视觉皮层17区进行了光镜和电镜检查，以确定年龄对神经元的影响。分析在半球外侧表面17区的一部分进行，该部分恰好在月状沟尾侧。对垂直取向的1微米厚切片中平均皮质深度的光镜测量显示，皮质厚度不会随年龄增长而明显变薄，神经元细胞核的平均直径也不会随年龄变化。基于在穿过整个皮质深度的1微米厚切片的250微米宽条带中含有细胞核的神经元轮廓计数，未检测到明显的神经元丢失。这些发现与我们对该皮质区域的电镜观察结果一致，因为在老年猴子中，除了存在一些脂褐素颗粒外，神经元几乎没有显示出明显的衰老细胞学证据，尽管神经毡中含有一些退化的小口径树突、有髓轴突和一些轴突终末的轮廓。老年动物的神经毡中存在直径约10微米或更大的大液泡。其中一些液泡似乎代表有髓轴突退化的晚期阶段，因为它们由一层薄的分层鞘膜界定。其他来源不明的大液泡通常含有膜性碎片，并且具有变薄的界膜。得出的结论是，老年恒河猴17区神经元的细胞体未显示出因年龄导致的明显结构变化，尽管神经毡中的一些神经元突起受到了影响。
