Baker R E, Van Pelt J
Netherlands Institute for Brain Research, Amsterdam, Netherlands.
Brain Res Dev Brain Res. 1997 Jan 2;98(1):21-9. doi: 10.1016/s0165-3806(96)00163-0.
Dendritic growth has been studied in long-term organotypic neonatal rat occipital neocortex grown either apart as isolated explants or in tandem as cocultures. Quantitative light microscopic measurement of dendritic and axonal branching patterns within the cortical slice was accomplished using rapid Golgi stained materials. In both isolates and cocultures the overall cellular organization of the slice was maintained over 4 weeks in vitro with morphologically distinguishable pyramidal and nonpyramidal neurons located within the same layers and with the same orientations as observed in situ. Long-term increases in the total length of basal dendrites, apical dendrite and axons were observed only in cocultures and were similar to growth patterns reported for in situ materials. Dendritic growth was mainly due to elongation of terminal dendritic segments. Surprisingly, isolated explants showed no long-term increases in total (basal) dendrites, apical dendrites or axons with time in vitro. A transient decrease in the number of basal dendritic segments and increase in terminal segment lengths at the end of the first week in vitro, however, was observed in nonpyramidal neurons. It is hypothesized that (i) afferent inputs and/or efferent targets develop only in cocultures and provide a crucial conditions for the continued growth of dendritic/axonal arborization for neocortical neurons in vitro, (ii) intrinsic interconnectivity within isolated explants is not sufficient to maintain long-term growth of neuritic arbors, and (iii) remodelling of dendritic arbors within isolated explants occurs at the same time as these explants are showing noticeable increases in the level of spontaneous bioelectric activity, which suggests that dendritic growth and network formation may be function dependent.
已在长期培养的新生大鼠枕叶新皮质的器官型组织中研究了树突生长情况，这些组织培养物既可以作为单独的外植体分离培养，也可以作为共培养物串联培养。使用快速高尔基染色材料对皮质切片内的树突和轴突分支模式进行了定量光学显微镜测量。在分离培养物和共培养物中，切片的整体细胞组织在体外4周内均得以维持，形态上可区分的锥体细胞和非锥体细胞位于同一层，且具有与原位观察到的相同方向。仅在共培养物中观察到基底树突、顶树突和轴突的总长度长期增加，且与原位材料报道的生长模式相似。树突生长主要是由于末端树突段的伸长。令人惊讶的是，分离的外植体在体外培养时，其基底树突、顶树突或轴突的总数并未随时间出现长期增加。然而，在非锥体细胞中，观察到体外培养第一周结束时基底树突段数量短暂减少，末端段长度增加。据推测：（i）传入输入和/或传出靶点仅在共培养物中发育，并为体外新皮质神经元树突/轴突分支的持续生长提供关键条件；（ii）分离外植体内的内在互连性不足以维持神经树突的长期生长；（iii）分离外植体内树突分支的重塑与这些外植体自发生物电活动水平显著增加同时发生，这表明树突生长和网络形成可能依赖于功能。
