Pichon Fabien, Ghysen Alain
Lab. Neurogénétique, INSERM E343, cc103, Université Montpellier II, Place Eugène Bataillon, 34095 Montpellier Cedex 5, France.
Evol Dev. 2004 May-Jun;6(3):187-93. doi: 10.1111/j.1525-142X.2004.04024.x.
The lateral line is a sensory system present in fish and amphibians. It is composed of discrete sense organs, the neuromasts, arranged on the head and body in species-specific patterns. The neuromasts are deposited by migrating primordia that originate from pre- and postotic placodes and follow defined pathways on the head and body. Here we examine the formation of the posterior lateral line (PLL), which extends rostrocaudally on the trunk and tail. In amphibians, the PLL neuromasts are deposited as a single wave from the head to the tip of the tail. In the zebrafish, however, the first wave of neuromast deposition forms but a rudimentary PLL, and several additional waves are needed to form the adult pattern. We show that the amphibian mode is also present in the sturgeon and therefore probably represents the primitive mode, whereas the zebrafish mode is highly conserved in several teleost species. A third mode is found in a subgroup of teleosts, the protacanthopterygians, and may represent a synapomorphy of this group. Altogether, the mode of formation of the embryonic PLL appears to have undergone remarkably few changes during the long history of anamniote evolution, even though large differences can be observed in the lateral line morphology of adult fishes.
侧线是鱼类和两栖动物所具有的一种感觉系统。它由离散的感觉器官——神经丘组成，这些神经丘以物种特有的模式排列在头部和身体上。神经丘由迁移的原基沉积而成，这些原基起源于耳前和耳后基板，并沿着头部和身体上特定的路径移动。在这里，我们研究了后外侧线（PLL）的形成，它在躯干和尾部上从吻端向尾端延伸。在两栖动物中，PLL神经丘以单个波的形式从头部沉积到尾尖。然而，在斑马鱼中，第一波神经丘沉积形成的只是一个初级的PLL，还需要几个额外的波来形成成年模式。我们发现鲟鱼也存在两栖动物的模式，因此这可能代表了原始模式，而斑马鱼的模式在几个硬骨鱼物种中高度保守。在硬骨鱼的一个亚群——原棘鳍鱼类中发现了第三种模式，这可能代表了该类群的一个共有衍征。总之，尽管成年鱼类的侧线形态存在很大差异，但在无羊膜动物漫长的进化历史中，胚胎PLL的形成模式似乎只发生了很少的变化。
