Abstract：
Within embryonic development, the occurrence of gastrulation is critical in the formation of multiple germ layers with many differentiative abilities. These cells are instructed through exposure to signalling molecules called morphogens. The secretion of morphogens from a source tissue creates a concentration gradient that allows distinct pattern formation in the receiving tissue. This review focuses on the morphogens Wnt and Fgf in zebrafish development. Wnt has been shown to have critical roles throughout gastrulation, including in anteroposterior patterning and neural posterisation. Fgf is also a vital signal, contributing to involution and mesodermal specification. Both morphogens have also been found to work in finely balanced synergy for processes such as neural induction. Thus, the signalling range of Wnts and Fgfs must be strictly controlled to target the correct target cells. Fgf and Wnts signal to local cells as well as to cells in the distance in a highly regulated way, requiring specific dissemination mechanisms that allow efficient and precise signalling over short and long distances. Multiple transportation mechanisms have been discovered to aid in producing a stable morphogen gradient, including short-range diffusion, filopodia-like extensions called cytonemes and extracellular vesicles, mainly exosomes. These mechanisms are specific to the morphogen that they transport and the intended signalling range. This review article discusses how spreading mechanisms in these two morphogenetic systems differ and the consequences on paracrine signalling, hence tissue patterning.
摘要：
在胚胎发育过程中,胃泌素的发生在具有许多分化能力的多个胚层的形成中至关重要。这些细胞是通过暴露于称为形态发生素的信号分子来指示的。从源组织分泌的形态发生素会产生浓度梯度，从而允许在接收组织中形成明显的图案。本文对斑马鱼发育中的形态发生原Wnt和Fgf进行了综述。Wnt已被证明在整个原肠胚形成过程中具有关键作用，包括前后模式和神经后验。Fgf也是一个重要的信号，有助于退化和中胚层规范。还发现两种形态发生素以精细平衡的协同作用用于过程如神经诱导。因此，必须严格控制Wnts和Fgfs的信号范围，以瞄准正确的目标细胞。Fgf和Wnts以高度调节的方式向本地细胞以及远处的细胞发出信号，需要特定的传播机制，以允许在短距离和长距离上有效和精确的信号。已经发现了多种运输机制来帮助产生稳定的形态发生原梯度，包括短程扩散，丝状足类延伸被称为胞质和细胞外囊泡，主要是外泌体。这些机制对它们运输的形态发生原和预期的信号传导范围是特异性的。这篇综述文章讨论了这两个形态发生系统中的传播机制如何不同以及对旁分泌信号的影响。因此组织图案化。
