Cohen-Gould L, Mikawa T
Department of Cell Biology and Anatomy, Cornell University Medical College, 1300 York Avenue, New York, New York, 10021, USA.
Dev Biol. 1996 Jul 10;177(1):265-73. doi: 10.1006/dbio.1996.0161.
In gastrulation stage embryos of birds and mammals, the heart field is established as mesodermal crescents flanking the area rostrolateral to Hensen's node. Subsequent fusion of the bilateral heart primordia gives rise to a single tubular heart consisting of two epithelial layers: an outer myocardium and an inner endocardium. To date, it is uncertain whether these two distinct cell types of the heart arise from common or separate progenitor populations of mesodermal cells within the heart field. By retroviral single cell marking and tracking, we examined the diversity of cell populations present in the heart field of stage 4 chicken embryos. Here we demonstrate that individual mesodermal cells in the heart field gave rise to a clone consisting only of one cell type, either endocardial or myocardial cells; i.e., 95.1% of the mesoderm-derived clones were localized in the myocardium, while 4.9% of them were found in endocardium. No clones containing both of these two cell types were detected. The results suggest that the heart field mesoderm at stage 4 consists of at least two distinct subpopulations, containing more premyocardial cells than preendocardial cells. If there exists a common precursor of both myocardial and endocardial cells, the lineage diversification must occur at or prior to the arrival of mesodermal cells to the heart field.
在鸟类和哺乳动物的原肠胚形成阶段胚胎中，心脏区域是作为位于亨森结 rostrolateral 区域两侧的中胚层新月形区域建立的。双侧心脏原基随后融合形成一个由两个上皮层组成的单一管状心脏：外层心肌和内层心内膜。迄今为止，尚不确定心脏的这两种不同细胞类型是源自心脏区域内中胚层细胞的共同祖细胞群还是分开的祖细胞群。通过逆转录病毒单细胞标记和追踪，我们研究了 4 期鸡胚心脏区域中存在的细胞群体的多样性。在这里我们证明，心脏区域中的单个中胚层细胞产生的克隆仅由一种细胞类型组成，要么是心内膜细胞要么是心肌细胞；即，95.1% 的中胚层来源克隆定位于心肌，而其中 4.9% 位于心内膜。未检测到包含这两种细胞类型的克隆。结果表明，4 期心脏区域中胚层至少由两个不同的亚群组成，其中心肌前体细胞比心内膜前体细胞更多。如果心肌细胞和心内膜细胞存在共同的前体，那么谱系多样化必定发生在中胚层细胞到达心脏区域之时或之前。
