Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, UT 84132, USA.
Development. 2011 Sep;138(17):3769-80. doi: 10.1242/dev.066852.
The maintenance of organs and their regeneration in case of injury are crucial to the survival of all animals. High rates of tissue turnover and nearly unlimited regenerative capabilities make planarian flatworms an ideal system with which to investigate these important processes, yet little is known about the cell biology and anatomy of their organs. Here we focus on the planarian excretory system, which consists of internal protonephridial tubules. We find that these assemble into complex branching patterns with a stereotyped succession of cell types along their length. Organ regeneration is likely to originate from a precursor structure arising in the blastema, which undergoes extensive branching morphogenesis. In an RNAi screen of signaling molecules, we identified an EGF receptor (Smed-EGFR-5) as a crucial regulator of branching morphogenesis and maintenance. Overall, our characterization of the planarian protonephridial system establishes a new paradigm for regenerative organogenesis and provides a platform for exploring its functional and evolutionary homologies with vertebrate excretory systems.
器官的维持和损伤后的再生对于所有动物的生存都是至关重要的。组织周转率高和几乎无限的再生能力使扁形动物成为研究这些重要过程的理想系统，但它们器官的细胞生物学和解剖学知之甚少。在这里，我们专注于扁形动物的排泄系统，它由内部原肾管组成。我们发现，这些原肾管组装成复杂的分支模式，其沿着长度具有定型的细胞类型顺序。器官再生可能起源于芽基中的前体结构，该前体结构经历广泛的分支形态发生。在信号分子的 RNAi 筛选中，我们鉴定出一种表皮生长因子受体（Smed-EGFR-5）作为分支形态发生和维持的关键调节剂。总的来说，我们对扁形动物原肾管系统的表征为再生器官发生建立了一个新的范例，并为探索其与脊椎动物排泄系统的功能和进化同源性提供了一个平台。
