Seil F J, Herndon R M, Tiekotter K L, Blank N K
Neurology Research, Veterans Affairs Medical Center, Portland, OR 97201.
J Comp Neurol. 1991 Nov 8;313(2):193-212. doi: 10.1002/cne.903130202.
This study was designed to examine the sequential changes in the developing granuloprival cerebellar culture. In this model of anomalous cerebellar development, organotypic cultures derived from newborn Swiss-Webster mice were exposed to the DNA synthesis inhibitor, cytosine arabinoside, at explantation and were fixed for electron microscopic examination on successive days in vitro. Similar developmental stages were compared in control explants. Granule cell destruction began early, and was widespread by 2 days in vitro, when oligodendrocyte destruction also began in treated cultures. A few granule cells survived, but no recognizable oligodendrocytes remained by 7 days in vitro, at a time when myelin was initially evident in control explants. Purkinje cell recurrent axon collateral sprouting began at 3 days in vitro in cultures exposed to cytosine arabinoside, and the sprouted terminals initially synapsed with Purkinje cell somata, somatic spines and dendritic shafts. Synapses with Purkinje cell dendritic spines developed later, at approximately the same time as parallel fiber-Purkinje cell dendritic spine synapses formed in control cultures. Astrocytic ensheathment of control Purkinje cells was well underway by 6 days in vitro and Purkinje cell somata were relatively rounded and almost completely ensheathed by 9 days in vitro. Glial ensheathment did not occur in cytosine arabinoside treated cultures, and Purkinje cell somata were scalloped at 7 days in vitro by excess impinging recurrent axon collateral terminals, and never developed the smooth contours characteristic of control Purkinje cells. Purkinje cell somatic spines persisted in treated explants, and reduction of excess extracellular space was delayed until 12 days in vitro, when most of the developmental changes had been completed. The earlier development of synapses by excess recurrent axon collateral terminals with Purkinje cell somata, somatic spines and dendritic shafts, followed by the later development of heterotypical synapses with dendritic spines, in parallel with synapse formation by normal presynaptic elements, suggests that the sequence of development of synapses is a function of the maturational state of the postsynaptic components.
本研究旨在检测发育中的颗粒细胞缺失型小脑培养物的序贯变化。在这种小脑发育异常模型中，将新生瑞士韦伯斯特小鼠的器官型培养物在植入时暴露于DNA合成抑制剂阿糖胞苷，并在体外连续几天固定以进行电子显微镜检查。在对照外植体中比较相似的发育阶段。颗粒细胞破坏早期开始，在体外2天时广泛存在，此时在处理的培养物中少突胶质细胞破坏也开始。少数颗粒细胞存活，但在体外7天时没有可识别的少突胶质细胞残留，而此时对照外植体中髓鞘最初明显可见。在暴露于阿糖胞苷的培养物中，浦肯野细胞的回返轴突侧支发芽在体外3天时开始，发芽的终末最初与浦肯野细胞胞体、体细胞棘和树突干形成突触。与浦肯野细胞树突棘的突触稍后形成，大约与对照培养物中平行纤维-浦肯野细胞树突棘突触形成的时间相同。对照浦肯野细胞的星形胶质细胞包被在体外6天时进展良好，浦肯野细胞胞体相对圆润，在体外9天时几乎完全被包被。在阿糖胞苷处理的培养物中未发生胶质细胞包被，在体外7天时，浦肯野细胞胞体因过多的回返轴突侧支终末撞击而呈扇形，且从未发育出对照浦肯野细胞特有的光滑轮廓。浦肯野细胞的体细胞棘在处理的外植体中持续存在，细胞外间隙过量减少延迟至体外12天，此时大多数发育变化已经完成。过多的回返轴突侧支终末与浦肯野细胞胞体、体细胞棘和树突干较早形成突触，随后与树突棘形成异型突触较晚，这与正常突触前成分形成突触平行，表明突触发育顺序是突触后成分成熟状态的函数。
