Moreno-Rodriguez R A, de la Cruz M V, Krug E L
Department of Cell Biology and Anatomy, Medical University of South Carolina, Charleston 29425, USA.
Anat Rec. 1997 May;248(1):84-92. doi: 10.1002/(SICI)1097-0185(199705)248:1<84::AID-AR10>3.0.CO;2-1.
We investigated potential early asymmetries in the distribution of mesenchymal cells within the inferior and superior AV cushions in the developing chick heart.
Chick embryos stages 16-20 HH were fixed, embedded in polyacrylamide, and the cell nuclei stained with propidium iodide. Cells counts were determined within the cardiac jelly of the atrioventricular canal (AV) by laser confocal microscopy in coronal planes spanning its entire length.
Our data show at the different stages studied, 16-20 HH, that the inferior AV cushion invariably contains more cells than the superior AV cushion. In the inferior cushion, the cell distribution is bimodal, i.e., the proximal and distal regions have more mesenchymal cells than the middle part of the AV canal. In the superior cushion, there is a increasing gradient of mesenchymal cells along the longitudinal axis from the atrium to the ventricle.
Our findings reveal that the temporal and spatial characteristics of mesenchyme formation in the inferior vs. superior AV cushion are different. This asymmetry suggests several potential hypotheses: (1) the distribution of the inducer molecule or its receptor has a distribution similar to that of mesenchymal cells, (2) the extracellular matrix has a differential composition or regionally-specific physical associations, (3) the endocardium is heterogeneous with respect to transformation capacity, or (4) these patterns result from an earlier inductive event. The potential importance of the observed asymmetries in the distribution of AV mesenchyme is discussed relative to localization patterns of molecules critical to successful cardiac morphogenesis and remodeling.
我们研究了发育中的鸡心脏内、上房室垫间间充质细胞分布可能存在的早期不对称性。
将16 - 20期HH的鸡胚固定，包埋于聚丙烯酰胺中，细胞核用碘化丙啶染色。通过激光共聚焦显微镜在跨越整个长度的冠状平面上测定房室管（AV）心胶内的细胞数量。
我们的数据显示，在研究的不同阶段（16 - 20期HH），下房室垫始终比上房室垫含有更多细胞。在下垫中，细胞分布呈双峰模式，即近端和远端区域比房室管中部有更多间充质细胞。在上垫中，从心房到心室沿纵轴间充质细胞呈递增梯度分布。
我们的研究结果表明，下、上房室垫间充质形成的时间和空间特征不同。这种不对称性提出了几个潜在的假设：（1）诱导分子或其受体的分布与间充质细胞的分布相似；（2）细胞外基质具有不同的组成或区域特异性物理联系；（3）心内膜在转化能力方面是异质的；或（4）这些模式源于更早的诱导事件。相对于对成功的心脏形态发生和重塑至关重要的分子的定位模式，讨论了观察到的房室间充质分布不对称性的潜在重要性。
