Widelitz Randall B, Baker Ruth E, Plikus Maksim, Lin Chih-Min, Maini Philip K, Paus Ralf, Chuong Cheng Ming
Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
Birth Defects Res C Embryo Today. 2006 Sep;78(3):280-91. doi: 10.1002/bdrc.20075.
Patterns form with the break of homogeneity and lead to the emergence of new structure or arrangement. There are different physiological and pathological mechanisms that lead to the formation of patterns. Here, we first introduce the basics of pattern formation and their possible biological basis. We then discuss different categories of skin patterns and their potential underlying molecular mechanisms. Some patterns, such as the lines of Blaschko and Naevus, are based on cell lineage and genetic mosaicism. Other patterns, such as regionally specific skin appendages, can be set by distinct combinatorial molecular codes, which in turn may be set by morphogenetic gradients. There are also some patterns, such as the arrangement of hair follicles (hair whorls) and fingerprints, which involve genetics as well as stochastic epigenetic events based on physiochemical principles. Many appendage primordia are laid out in developmental waves. In the adult, some patterns, such as those involving cycling hair follicles, may appear as traveling waves in mice. Since skin appendages can renew themselves in regeneration, their size and shape can still change in the adult via regulation by hormones and the environment. Some lesion patterns are based on pathological changes involving the above processes and can be used as diagnostic criteria in medicine. Understanding the different mechanisms that lead to patterns in the skin will help us appreciate their full significance in morphogenesis and medical research. Much remains to be learned about complex pattern formation, if we are to bridge the gap between molecular biology and organism phenotypes.
模式随着同质性的打破而形成，并导致新结构或排列的出现。存在不同的生理和病理机制导致模式的形成。在此，我们首先介绍模式形成的基础知识及其可能的生物学基础。然后我们讨论不同类别的皮肤模式及其潜在的分子机制。一些模式，如布拉斯科线和痣，基于细胞谱系和遗传镶嵌现象。其他模式，如区域特异性皮肤附属器，可以由不同的组合分子编码设定，而这些编码反过来又可能由形态发生梯度设定。还有一些模式，如毛囊的排列（发旋）和指纹，涉及遗传学以及基于物理化学原理的随机表观遗传事件。许多附属器原基以发育波的形式排列。在成体中，一些模式，如涉及周期性毛囊的模式，在小鼠中可能表现为行波。由于皮肤附属器在再生过程中可以自我更新，它们的大小和形状在成体中仍可通过激素和环境的调节而改变。一些病变模式基于涉及上述过程的病理变化，可作为医学诊断标准。了解导致皮肤模式的不同机制将有助于我们认识它们在形态发生和医学研究中的全部意义。如果我们要弥合分子生物学与生物体表型之间的差距，关于复杂模式形成仍有许多有待了解的地方。
