Parnass Z, Tashiro A, Yuste R
Department of Biological Sciences, Columbia University, New York, New York 10027, USA.
Hippocampus. 2000;10(5):561-8. doi: 10.1002/1098-1063(2000)10:5<561::AID-HIPO6>3.0.CO;2-X.
Dendritic spines are targets of most excitatory inputs in the central nervous system (CNS) and are morphologically heterogeneous. Ultrastructural studies have traditionally classified spines into four major categories (filopodia, stubby, thin, and mushroom) based on their distinct morphologies. The recent discovery of rapid morphological plasticity of spines has raised the possibility that those categories, rather than being intrinsically different populations of spines, represent instead temporal snapshots of a single dynamic phenomenon. We examined this question with two-photon time-lapse imaging of developing hippocampal pyramidal neurons, transfected with E-GFP in cultured slices. After blind scoring to morphologically classify spines into the four traditional groups, we analyzed the fate of populations of spines over a period of 2-4 h. We found considerable morphological conversions among all categories, although systematic trends were detected. While most stubbies and spines (defined for our analysis as the combination of thin and mushroom protrusions) retained their basic morphologies, most filopodia transformed into stubbies and spines, although they could also extend out of existing spines. Our results suggest that in developing hippocampal pyramidal neurons, traditional morphological distinctions are stable over short (<4 h) periods of time, but that at the same time, considerable mixing among these groups takes place.
树突棘是中枢神经系统（CNS）中大多数兴奋性输入的靶点，且在形态上具有异质性。传统的超微结构研究根据其不同形态将树突棘分为四大类（丝状伪足、短粗型、细型和蘑菇型）。最近关于树突棘快速形态可塑性的发现提出了一种可能性，即这些类别并非本质上不同的树突棘群体，而是单一动态现象的时间快照。我们在培养切片中对转染了E - GFP的发育中的海马锥体神经元进行双光子延时成像，以研究这个问题。在对树突棘进行盲态评分以将其形态学分类为四个传统组后，我们分析了2 - 4小时内树突棘群体的命运。我们发现所有类别之间都存在相当多的形态转变，尽管检测到了系统趋势。虽然大多数短粗型和棘状突起（在我们的分析中定义为细型和蘑菇型突起的组合）保持其基本形态，但大多数丝状伪足转变为短粗型和棘状突起，尽管它们也可以从现有的树突棘中延伸出来。我们的结果表明，在发育中的海马锥体神经元中，传统的形态学差异在短时间（<4小时）内是稳定的，但与此同时，这些组之间发生了相当多的混合。
