Watanabe H, Washioka H, Tonosaki A
Anat Rec. 1986 Jan;214(1):82-8. doi: 10.1002/ar.1092140114.
"Cholinergic" synapses of the bullfrog sympathetic ganglion cells were investigated with thin sectioning, complementary freeze-fracturing, and deep-etching methods after glutaraldehyde fixation. The protoplasmic (-fracture) face (PF) of the postsynaptic membrane was characterized by intramembranous particles (IMPs), 3,500/micron 2 in density, consisting of larger particles, 10-12 nm in diameter, and smaller ones, 8-9 nm; the complementary exoplasmic (-fracture) face (EF) contained larger and smaller IMPs, 750/micron 2 in density, and numbers of pits. By close inspection of the sections and freeze-fracture replicas at high magnification and with deep-etching in particular, it was concluded that aggregated IMPs might represent transmembranous components and that the particulate entities existing in the postsynaptic active zones might be larger in number than those exposed to view and counted here in the "cholinergic" synapses. An individual IMP often appeared to consist of five or six subunits arranged in a rosette with a central pit. These findings suggest that the aggregated IMPs, particularly the larger ones, may be closely related to the structure of the nicotinic ACh receptor-ion channel complex.
用戊二醛固定后，采用超薄切片、互补冷冻蚀刻和深度蚀刻方法，对牛蛙交感神经节细胞的“胆碱能”突触进行了研究。突触后膜的原生质（断裂）面（PF）的特征是存在膜内颗粒（IMPs），密度为3500个/μm²，由直径为10 - 12nm的较大颗粒和8 - 9nm的较小颗粒组成；互补的细胞外（断裂）面（EF）含有密度为750个/μm²的较大和较小的IMPs以及许多凹坑。通过高倍仔细检查切片和冷冻蚀刻复制品，特别是深度蚀刻复制品，得出的结论是，聚集的IMPs可能代表跨膜成分，并且在突触后活性区存在的颗粒实体数量可能比在“胆碱能”突触中这里所观察到并计数的要多。单个IMPs通常似乎由五六个亚基组成，排列成带有中央凹坑的玫瑰花结。这些发现表明，聚集的IMPs，特别是较大的IMPs，可能与烟碱型乙酰胆碱受体 - 离子通道复合物的结构密切相关。
