Miyata Takaki
Department of Anatomy and Cell Biology, Nagoya University Graduate School of Medicine, 65 Tsurumai, Showaku, Nagoya, 466-8550 Japan.
Nihon Shinkei Seishin Yakurigaku Zasshi. 2005 Aug;25(4):175-81.
Studying the mechanism of brain formation is important for the understanding of physiological and pathological conditions of the human brain and also for development of regenerative medicine. Slice culture methods coupled with sporadic labeling of cells with fluorescent materials are useful to directly observe dynamic behaviors of cells in the brain primordium. In the developing mouse neocortex, "radial glial cells" which had been thought to be non-neuronogenic are now regarded as a main progenitor population for neuron production, revitalizing Setsuya Fujita's "matrix cell theory" (J Comp Neurol, 120: 37-42, 1963). During mitosis at the ventricular surface, each progenitor cell maintains its process extended to the pial surface, giving the pial process to one of its daughter cells. Process-inheriting daughter cells, including neurons, utilize the inherited pial processes for their migration. The other histogenetic strategy that the developing neocortex employs for efficient segregation of neurons from the progenitor cells' territory is the use of the non-surface mitoses (divisions away from the ventricular surface). The non-surface-dividing progenitor cells born at the ventricular surface subsequently lose their ventricular attachment and then divide at a non-surface position, giving rise to pairs of neurons just beneath a layer into which young neurons should be inserted.
研究大脑形成机制对于理解人类大脑的生理和病理状况以及再生医学的发展都很重要。切片培养方法与用荧光材料对细胞进行零星标记相结合，有助于直接观察脑原基中细胞的动态行为。在发育中的小鼠新皮层中，曾被认为不具有神经元生成能力的“放射状胶质细胞”，如今被视为神经元产生的主要祖细胞群体，这使藤田哲也的“基质细胞理论”（《比较神经学杂志》，120: 37 - 42, 1963）得以复兴。在脑室表面进行有丝分裂时，每个祖细胞保持其延伸至软脑膜表面的突起，并将软脑膜突起传递给其一个子细胞。包括神经元在内的继承突起的子细胞利用继承的软脑膜突起进行迁移。发育中的新皮层用于将神经元与祖细胞区域有效分离的另一种组织发生策略是利用非表面有丝分裂（在远离脑室表面的位置进行分裂）。在脑室表面产生的非表面分裂祖细胞随后失去与脑室的附着，然后在非表面位置进行分裂，在年轻神经元应插入的层下方产生成对的神经元。
