Venters Sara J, Ordahl Charles P
Department of Anatomy and Cardiovascular Research Institute, University of California San Francisco, San Francisco, CA 94143, USA.
Anat Embryol (Berl). 2005 Jul;209(6):449-60. doi: 10.1007/s00429-005-0461-2. Epub 2005 May 13.
To determine if somitic stem cell pools could be identified by an intrinsic difference in mitotic behaviour, the orientation of mitoses in the dermomyotome epithelium was analysed. We describe a concentration of apico-basal mitoses within the dermomyotome dorsomedial lip (DML). The occurrence of apico-basal divisions is closely associated with asymmetric localisation of the notch pathway factor numb, allowing description of such divisions as asymmetric. In contrast, planar divisions, occurring in the plane of the epithelium, are symmetric. Further, we show that the DML environmental niche is sufficient to promote numb expression in epaxial dermomyotome tissue that does not normally express this factor. These data provide, for the first time, a non-retrospective tracing analysis of the mechanism by which the DML fulfils the stem-cell pool role it plays during epaxial primary myotome morphogenesis.
为了确定是否可以通过有丝分裂行为的内在差异来识别体节干细胞库，我们分析了皮肌节上皮细胞有丝分裂的方向。我们描述了皮肌节背内侧唇（DML）内顶-基有丝分裂的集中情况。顶-基分裂的发生与Notch信号通路因子Numb的不对称定位密切相关，因此可将此类分裂描述为不对称分裂。相比之下，发生在上皮平面内的平面分裂是对称的。此外，我们发现DML的微环境足以促进通常不表达该因子的轴上肌皮节组织中Numb的表达。这些数据首次提供了一种非回顾性的追踪分析，揭示了DML在轴上初级肌节形态发生过程中发挥干细胞库作用的机制。
