Morris-Wiman J, Brinkley L
Department of Orthodontics, College of Dentistry, University of Florida, Gainesville 32610.
Anat Embryol (Berl). 1993 Jul;188(1):75-85. doi: 10.1007/BF00191453.
The sequence of events and the distribution of extracellular matrix (ECM) components was examined during mouse secondary palatal shelf elevation in an in vitro model using standard roller tube culture methods developed for the culture of early embryos. In this culture system, the morphological changes associated with remodelling and reorientation of the palatal shelves of gestational day 13 mouse fetuses were similar to those observed in vivo. However, in specimens explanted 24-30 h prior to reorientation in vivo, remodelling began rapidly after explantation, and significant reorientation was accomplished within 4 h. Midline contact between the shelves did not occur until after 18 h in vitro, concomitant with shelf growth. Therefore, in this in vitro model, events related to palatal shelf remodelling and reorientation can be distinguished from those related to shelf growth. We used this in vitro model to characterize the transient changes in ECM distribution and accumulation that occur concomitant with events in shelf remodelling. Our results show that, during rapid remodelling in vitro, the relative distributions of collagen III, fibronectin and hyaluronate, as visualized by immunofluorescent staining, decreased within specific regions of the mesenchymal compartment. In contrast, the distribution of collagen I within the mesenchyme increased, and the distribution of tenascin did not change significantly. All molecules examined, except tenascin, showed changes in distribution within the basement membrane. These patterns of distribution are similar to those observed during more gradual remodelling in vivo. During remodelling in vitro, the deposition of [3H]-glucosamine- and [3H]-proline-labelled components of the ECM, as visualized by autoradiography, was greatest during the first 3 h of culture. During this period, labelled ECM accumulated within specific regions of the mesenchyme and palatal epithelial basement membrane. Uptake was reduced dramatically during the subsequent 3 h in culture and was restricted mainly to the palatal epithelium and its underlying basement membrane. The in vitro system permitted the characterization of early events in shelf remodelling leading to reorientation. Results suggest that remodelling is accompanied by rapid, local accumulation of ECM in specific regions of the palatal shelf previously thought to play a role in the process.
利用为早期胚胎培养开发的标准滚管培养方法，在体外模型中研究了小鼠次生腭架抬高过程中的事件序列和细胞外基质（ECM）成分的分布。在这个培养系统中，与妊娠第13天小鼠胎儿腭架重塑和重新定向相关的形态学变化与体内观察到的相似。然而，在体内重新定向之前24 - 30小时取出的标本中，取出后重塑迅速开始，并且在4小时内完成了显著的重新定向。直到体外培养18小时后，腭架之间才发生中线接触，这与腭架生长同时发生。因此，在这个体外模型中，与腭架重塑和重新定向相关的事件可以与与腭架生长相关的事件区分开来。我们使用这个体外模型来表征与腭架重塑事件同时发生的ECM分布和积累的瞬时变化。我们的结果表明，在体外快速重塑过程中，通过免疫荧光染色观察到，III型胶原、纤连蛋白和透明质酸在间充质区室的特定区域内的相对分布减少。相反，I型胶原在间充质中的分布增加，而腱生蛋白的分布没有显著变化。除腱生蛋白外，所有检测的分子在基底膜内的分布都有变化。这些分布模式与在体内更渐进的重塑过程中观察到的相似。在体外重塑过程中，通过放射自显影观察到，ECM的[3H] - 葡糖胺和[3H] - 脯氨酸标记成分的沉积在培养的前3小时最大。在此期间，标记的ECM在间充质和腭上皮基底膜的特定区域内积累。在随后的3小时培养中摄取显著减少，并且主要局限于腭上皮及其下方的基底膜。这个体外系统允许对导致重新定向的腭架重塑早期事件进行表征。结果表明，重塑伴随着ECM在腭架特定区域的快速、局部积累，这些区域以前被认为在这个过程中起作用。
