Hirokawa N
Department of Anatomy and Cell Biology, School of Medicine, University of Tokyo, Japan.
Neurosci Res. 1989 Feb;6(3):269-75. doi: 10.1016/0168-0102(89)90066-7.
The cytoskeletal architecture of the postsynaptic cytoplasm in the cerebellar cortex of mice and rats was observed by quick-freeze, deep-etch electron microscopy. The postsynaptic cytoplasm was mainly filled with a network of actin filaments (approximately 8 nm in width). The tips of the actin filaments were closely associated with the true inner side of the postsynaptic membranes. However, the organization of the actin filaments was distinct depending on the types of synapses. In axosomatic synapses the actin filaments tended to run randomly and form a network while in the postsynaptic spine, such as Purkinje cell dendritic spines, the actin filaments were mainly arranged parallel to the stalk of the spines. Only a few actin filaments were found in the postsynaptic cytoplasm of some axodendritic synapses such as mossy fiber-granule cell synapses. In most cases a mesh of fine strands (approximately 6 nm in width) and granular substances was observed just underneath the postsynaptic membranes which also associated with actin filaments. The arrangement of actin filaments in the spine does not support the possibility of constriction of spines as a basis for long-term depression (LTD).
通过快速冷冻、深度蚀刻电子显微镜观察了小鼠和大鼠小脑皮质中突触后细胞质的细胞骨架结构。突触后细胞质主要充满了肌动蛋白丝网络（宽度约为8纳米）。肌动蛋白丝的末端与突触后膜的真正内侧紧密相连。然而，肌动蛋白丝的组织方式因突触类型而异。在轴体突触中，肌动蛋白丝倾向于随机排列并形成网络，而在突触后棘，如浦肯野细胞树突棘中，肌动蛋白丝主要平行于棘的柄部排列。在一些轴树突触，如苔藓纤维-颗粒细胞突触的突触后细胞质中仅发现少数肌动蛋白丝。在大多数情况下，在突触后膜下方还观察到与肌动蛋白丝相关的细链（宽度约为6纳米）和颗粒物质组成的数据。棘中肌动蛋白丝的排列不支持将棘的收缩作为长时程抑制（LTD）基础的可能性。
