目的 确定老年大鼠海马神经元的细胞核是否萎缩。  方法 从1、2和3年龄的正常雄性SD大鼠（每个年龄组5只）的一侧（随机选择）大脑半球，完整剥离海马结构，甲基丙烯酸树脂包埋后作连续切片，厚 40 μm， 等距随机抽选3~4张切片，过碘酸、席夫试剂和苏木精染色。用体视学方法估计海马神经元细胞核的大小：先用光学体视框均匀随机抽选细胞核，然后在其最大轮廓的聚焦平面（光学切片）测其费雷特（Feret）直径作为细胞核直径，然后在其核仁的最清晰聚焦平面用核距测量法测其体积。  结果 整个海马内，3个年龄组的神经元细胞核平均直径为8.7~9.2 μm，平均体积为392~457 μm3，两者组间差异皆无显著性。海马各区——CA区（海马本部）、齿状回或下托的细胞核平均直径或体积组间差异也无显著性。  结论 从中年到老年，大鼠整个海马内神经元细胞核的大小未发现明显的年龄相关变化。

Objective To determine if there is atrophy of neuronal nuclei in the aging rat hippocampus.  Methods  The entire hippocampal formation in a cerebral hemisphere (on a random side) was removed from normal male SD rats aged 1, 2 and 3 years (each age-group 5 rats), serial sections (section thickness 40 μm) were cut after embedding in a resin of glycol methacrylate, and 3-4 sections were systematically sampled and stained with periodic acid, Schiff’s reagent and hematoxylin. The nuclear sizes of hippocampal neurons were estimated with stereological methods, first, the nuclei were sampled in a uniform random way using the optical disector; then, a Feret diameter of the largest nuclear profile at its focal plane (optical section) was measured as the nuclear diameter, and the nuclear volume was measured at the clearest focal plane of the nucleolus with the nucleator.   Results The mean diameters and volumes of the neuronal nuclei in the whole hippocampus were 8.7-9.2 μm and 392-457 μm3, respectively, in the 3 age-groups, without significant statistical difference between groups. There were no significant difference between groups, either, in the nuclear diameter or volume in each hippocampal region——the CA (hippocampus proper), dentate gyrus or subiculum.   Conclusion  In general, no age-related changes have been observed in the nuclear sizes of neurons in the whole hippocampus in the rat from middle to old age.