Hirokawa N
J Comp Neurol. 1979 May 1;185(1):107-19. doi: 10.1002/cne.901850107.
The mechanism of synaptogenesis between dendritic spines of Purkinje cells and parallel fibers in the chicken cerebellum was studied through chronic treatment and immunocytochemistry of beta-Bungarotoxin (beta-BT). Attention was directed to the question of whether the presynaptic specializations (presynaptic vesicular grids composed of presynaptic dense projections and associated vesicles) of the parallel fibers can differentiate in the absence of the Purkinje cells. Normal cerebella from 18-day and 21-day chick embryos, incubated with beta-BT and reacted with HRP-labeled anti beta-BT guinea pig IgG, showed a positive HRP reaction on Purkinje cells but not on external and internal granule cells. Thus, in chicken cerebellum, beta-BT primarily affects Purkinje cells. When beta-BT was applied to chick embryos at 3-day intervals, beginning on the 4th day of incubation, the cerebella were markedly reduced in size and most of the Purkinje cells as well as the nerve fibers in the white matter disappeared between the 18th and the 21st day of incubation. Folia of the 21st day experimental cerebella were irregular in shape and the area of the midsagittal section was one fourth that of the controls. In the 21st day cerebella treated with beta-BT, the majority of Purkinje cells disappear. However, the external granule cells remain intact and showed the usual mitotic activity. The majority of the inner granule cells were normal. Some of the parallel fibers, which display presynaptic vesicular grids, established synaptic contact with stellate cells and the dendritic spines of the few Purkinje cells that survived the treatment. However, vast areas of the molecular layer contained neither dendrites of Purkinje cells, nor parallel fibers displaying presynaptic vesicular grids devoid of their postsynaptic counterpart. In such areas, the molecular layer consisted of parallel fibers of uniform diameter, some of which contained accumulations of vesicles, but displaying no presynaptic dense projections. This suggests that parallel fibers may not be able to completely develop the presynaptic vesicular grids in the absence of their target cells.
通过β-银环蛇毒素（β-BT）的慢性处理和免疫细胞化学方法，研究了鸡小脑浦肯野细胞树突棘与平行纤维之间突触形成的机制。研究重点关注平行纤维的突触前特化结构（由突触前致密突起和相关囊泡组成的突触前囊泡网格）在没有浦肯野细胞的情况下是否能够分化。用β-BT孵育18天和21天鸡胚的正常小脑，并与辣根过氧化物酶标记的抗β-BT豚鼠IgG反应，结果显示浦肯野细胞有阳性辣根过氧化物酶反应，而外颗粒细胞和内颗粒细胞则没有。因此，在鸡小脑中，β-BT主要影响浦肯野细胞。从孵育第4天开始，每隔3天给鸡胚应用β-BT，在孵育第18天至第21天期间，小脑体积明显减小，大多数浦肯野细胞以及白质中的神经纤维消失。第21天实验性小脑的叶片形状不规则，矢状面面积为对照组的四分之一。在第21天用β-BT处理的小脑中，大多数浦肯野细胞消失。然而，外颗粒细胞保持完整并显示出正常的有丝分裂活性。大多数内颗粒细胞正常。一些显示突触前囊泡网格的平行纤维与星形细胞以及少数在处理后存活的浦肯野细胞的树突棘建立了突触联系。然而，分子层的大片区域既没有浦肯野细胞的树突，也没有显示出没有突触后对应物的突触前囊泡网格的平行纤维。在这些区域，分子层由直径均匀的平行纤维组成，其中一些含有囊泡聚集，但没有突触前致密突起。这表明在没有靶细胞的情况下，平行纤维可能无法完全发育突触前囊泡网格。
