Huttenlocher P R
Brain Res. 1979 Mar 16;163(2):195-205. doi: 10.1016/0006-8993(79)90349-4.
Density of synaptic profiles in layer 3 of middle frontal gyrus was quantitated in 21 normal human brains ranging from newborn to age 90 years. Synaptic profiles could be reliably demonstrated by the phosphotungstic acid method (Bloom and Aghajanian) in tissue fixed up to 36 h postmortem. Synaptic density was constant throughout adult life (ages 16--72 years) with a mean of 11.05 X 10(8) synapses/cu.mm +/- 0.41 S.E.M. There was a slight decline in synaptic density in brains of the aged (ages 74--90 years) with a mean of 9.56 X 10(8) synapses/cu.mm +/- 0.28 S.E.M. in 4 samples (P less than 0.05). Synaptic density in neonatal brains was already high--in the range seen in adults. However, synaptic morphology differed; immature profiles had an irregular presynaptic dense band instead of the separate presynaptic projections seen in mature synapses. Synaptic density increased during infancy, reaching a maximum at age 1--2 years which was about 50% above the adult mean. The decline in synaptic density observed between ages 2--16 years was accompanied by a slight decrease in neuronal density. Human cerebral cortex is one of a number of neuronal systems in which loss of neurons and synapses appears to occur as a late developmental event.
对21例年龄从新生儿到90岁的正常人类大脑，定量分析了额中回第3层的突触形态密度。用磷钨酸法（布鲁姆和阿加贾尼安法）可在死后长达36小时固定的组织中可靠地显示突触形态。在整个成年期（16 - 72岁），突触密度保持恒定，平均为11.05×10⁸个突触/立方毫米±0.41标准误。在老年大脑（74 - 90岁）中，突触密度略有下降，4个样本的平均值为9.56×10⁸个突触/立方毫米±0.28标准误（P<0.05）。新生儿大脑中的突触密度已经很高，处于成人所见的范围内。然而，突触形态有所不同；未成熟的突触形态具有不规则的突触前致密带，而不是成熟突触中所见的独立突触前突起。突触密度在婴儿期增加，在1 - 2岁时达到最大值，比成人平均值高出约50%。在2 - 16岁之间观察到的突触密度下降伴随着神经元密度的轻微降低。人类大脑皮层是许多神经元系统之一，在这些系统中，神经元和突触的丧失似乎是一种晚期发育事件。
