Devon R M, Jones D G
Dev Neurosci. 1981;4(5):351-62. doi: 10.1159/000112775.
The ultrastructure of synapses from the molecular layer of parietal cortex was examined in male rats aged between 7 and 75 days. Two groups were compared, one group consisting of rats anaesthetized with 50 mg/kg pentobarbitone and the other consisting of those killed by stunning across the back of the neck. Various synaptic parameters were analyzed. In the anaesthetized material, the sectioned area of the pre-synaptic terminals decreases between 7 and 75 days, as does the number of terminals containing intraterminal profiles other than synaptic vesicles. Mean synaptic vesicle number per terminal increases, while the remaining parameters fluctuate over the developmental period. Comparing these data with those from the unanaesthetized material, the only parameters showing similar trends are the pre-synaptic terminal area, the mean vesicle number per terminal, and the length of the postsynaptic thickening. The remaining parameters are comparable up to 15 or 21 days postnatally, after which they diverge. The percentage of terminals containing intraterminal profiles, the terminal perimeter and the mean vesicle density in the unanaesthetized terminals all show increased values. The form factor indicates these terminals are more ellipsoidal by 75 days, while the mean synaptic curvature is more positive by 75 days. It is concluded that the synaptic organization of the early terminals differs from that of the older ones, and this may be related to different mechanisms of transmitter storage and release.
对7至75日龄雄性大鼠顶叶皮质分子层突触的超微结构进行了检查。比较了两组，一组是用50mg/kg戊巴比妥麻醉的大鼠，另一组是通过颈部背部电击处死的大鼠。分析了各种突触参数。在麻醉材料中，突触前终末的横截面积在7至75日龄之间减小，含有除突触小泡之外的终末内轮廓的终末数量也减少。每个终末的平均突触小泡数量增加，而其余参数在发育期间波动。将这些数据与未麻醉材料的数据进行比较，显示出相似趋势的唯一参数是突触前终末面积、每个终末的平均小泡数量和突触后增厚的长度。其余参数在出生后15或21天之前具有可比性，之后它们出现差异。未麻醉终末中含有终末内轮廓的终末百分比、终末周长和平均小泡密度均显示增加的值。形态因子表明，到75日龄时这些终末更呈椭圆形，而平均突触曲率到75日龄时更趋正向。结论是早期终末的突触组织与较成熟终末的不同，这可能与递质储存和释放的不同机制有关。
