Grosse G, Tapp R, Wartenberg M, Sauer H, Fox P A, Grosse J, Gratzl M, Bergmann M
Institut für Anatomie, Universitätsklinikum Charité, Humboldt-Universität Berlin, Germany.
J Neurosci Res. 1998 Mar 1;51(5):602-11. doi: 10.1002/(SICI)1097-4547(19980301)51:5<602::AID-JNR7>3.0.CO;2-J.
Mossy fiber boutons are the sites of synaptic signalling between hippocampal granule and pyramidal neurons. We studied the formation and localization of these terminals during development of prenatal hippocampal neurons in primary culture. Using the synaptic vesicle membrane proteins synaptophysin and synaptoporin as markers we observed that both proteins were mainly localized in perikarya and processes of fetal hippocampal neurons during the first days in vitro (DIV). Following DIV 6 synaptophysin was present in small terminals. After DIV 20 in addition large terminals immunoreactive for synaptophysin and synaptoporin were found, which were identified by electron microscopy as mossy fiber boutons impinging on pyramidal neuron dendrites. Synaptic vesicles and endosomes in the mossy fiber boutons were labeled when incubated with exogenous horseradish peroxidase, indicating that they were competent for exo-endocytosis. Taken together, our data show that hippocampal granule neurons grown in dissociated primary cultures form mossy fiber boutons containing synaptophysin and synaptoporin at pyramidal cell dendrites. Since the composition and the characteristic morphology of mossy fiber boutons formed in vitro is the same as observed in vivo we conclude that their development follows an intrinsic program.
苔藓纤维终扣是海马颗粒神经元与锥体细胞之间突触信号传递的位点。我们研究了原代培养的产前海马神经元发育过程中这些终末的形成和定位。以突触囊泡膜蛋白突触素和突触孔蛋白作为标志物，我们观察到在体外培养的最初几天（体外培养天数，DIV），这两种蛋白主要定位于胎儿海马神经元的胞体和突起中。在体外培养6天后，突触素出现在小终末中。在体外培养20天后，还发现了对突触素和突触孔蛋白呈免疫反应性的大终末，通过电子显微镜鉴定为撞击锥体细胞树突的苔藓纤维终扣。当与外源性辣根过氧化物酶孵育时，苔藓纤维终扣中的突触囊泡和内体被标记，表明它们具有胞吐 - 内吞作用的能力。综上所述，我们的数据表明，在解离的原代培养物中生长的海马颗粒神经元在锥体细胞树突处形成含有突触素和突触孔蛋白的苔藓纤维终扣。由于体外形成的苔藓纤维终扣的组成和特征形态与体内观察到的相同，我们得出结论，它们的发育遵循内在程序。
