Abstract：
The salivary gland undergoes branching morphogenesis to elaborate into a tree-like structure with numerous saliva-secreting acinar units, all joined by a hierarchical ductal system. The expansive epithelial surface generated by branching morphogenesis serves as the structural basis for the efficient production and delivery of saliva. Here, we elucidate the process of salivary gland morphogenesis, emphasizing the role of mechanics. Structurally, the developing salivary gland is characterized by a stratified epithelium tightly encased by the basement membrane, which is in turn surrounded by a mesenchyme consisting of a dense network of interstitial matrix and mesenchymal cells. Diverse cell types and extracellular matrices bestow this developing organ with organized, yet spatially varied mechanical properties. For instance, the surface epithelial sheet of the bud is highly fluidic due to its high cell motility and weak cell-cell adhesion, rendering it highly pliable. In contrast, the inner core of the bud is more rigid, characterized by reduced cell motility and strong cell-cell adhesion, which likely provide structural support for the tissue. The interactions between the surface epithelial sheet and the inner core give rise to budding morphogenesis. Furthermore, the basement membrane and the mesenchyme offer mechanical constraints that could play a pivotal role in determining the higher-order architecture of a fully mature salivary gland.
摘要：
唾液腺经历分支形态发生，以形成具有许多分泌唾液的腺泡单元的树状结构，全部由分层导管系统连接。通过分支形态发生产生的扩张性上皮表面充当有效产生和递送唾液的结构基础。这里,我们阐明了唾液腺形态发生的过程，强调力学的作用。在结构上,正在发育的唾液腺的特征是由基底膜紧密包裹的复层上皮，它又被间质包围，由间质基质和间充质细胞的密集网络组成。不同的细胞类型和细胞外基质赋予这个发育中的器官有组织，然而空间变化的机械性能。例如,芽的表面上皮片由于其高细胞运动性和弱细胞间粘附性而具有高度的流动性，使其高度柔韧。相比之下,芽的内核更坚硬，以细胞运动性降低和细胞间粘附力强为特征，这可能为组织提供结构支撑。表面上皮片和内核之间的相互作用引起出芽形态发生。此外，基底膜和间充质提供了机械约束，可能在确定完全成熟的唾液腺的高阶结构中起关键作用。
