Okamoto Eri, Van Mai Hieu, Ishimatsu Atsushi, Tanaka Mikiko
1School of Life Science and Technology, Tokyo Institute of Technology, B-17, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Japan.
2Graduate School of Fisheries and Environmental Sciences, Nagasaki University, 1-14 Bunkyomachi, Nagasaki, 851-8521 Japan.
Zoological Lett. 2018 Aug 11;4:23. doi: 10.1186/s40851-018-0105-z. eCollection 2018.
Mudskippers are amphibious fishes that use their pectoral fins to move on land. Their pectoral fins are specifically modified for terrestrial locomotion. Studies of the anatomy and kinematics of adult mudskippers suggest that modifications of the pectoral fins, such as their protrusion and elongation of the proximal radials, may provide greater control and flexibility in pectoral fin-based locomotion. However, it is unknown when and how the unique features of these pectoral fins form during the development of mudskippers, which begin life as a planktonic organism.
Here we examined the developmental process of the pectoral fins of the mudskipper to address these questions. We also observed other developmental characteristics to provide clarified descriptions, including indicative morphological changes that occur during metamorphosis.
Our results show that the localized cell division of the proximal part of the endoskeletal disc-the primordium of the proximal radials-and subsequent cell division along the proximal-distal axis, which is restricted to the distal part of the disc during the larva-to-juvenile transition (metamorphosis), lead to the elongation of the proximal radials.
弹涂鱼是一种两栖鱼类，它们利用胸鳍在陆地上移动。它们的胸鳍经过特殊改造以适应陆地运动。对成年弹涂鱼的解剖学和运动学研究表明，胸鳍的改造，如近端桡骨的突出和伸长，可能在基于胸鳍的运动中提供更大的控制和灵活性。然而，这些胸鳍的独特特征在弹涂鱼的发育过程中何时以及如何形成尚不清楚，弹涂鱼最初是以浮游生物的形式开始生命的。
在这里，我们研究了弹涂鱼胸鳍的发育过程以解决这些问题。我们还观察了其他发育特征以提供更清晰的描述，包括变态过程中发生的指示性形态变化。
我们的结果表明，内骨骼盘近端部分（近端桡骨的原基）的局部细胞分裂以及随后沿近端 - 远端轴的细胞分裂（在幼虫到幼体过渡（变态）期间仅限于盘的远端部分）导致近端桡骨伸长。
