Department of Biology, DePauw University, Greencastle, Indiana.
University of Houston College of Optometry, Houston, Texas.
Dev Dyn. 2019 Nov;248(11):1155-1174. doi: 10.1002/dvdy.88. Epub 2019 Jul 30.
Aquatic species in several clades possess cement glands producing adhesive secretions of various strengths. In vertebrates, transient adhesive organs have been extensively studied in Xenopus laevis, other anurans, and in several fish species. However, the development of these structures is not fully understood.
Here, we report on the development and functional morphology of the adhesive gland of a giant danio species, Devario malabaricus. We found that the gland is localized on the larval head, is composed of goblet-like secretory cells framed by basal, bordering, and intercalated apical epithelial cells, and is innervated by the trigeminal ganglion. The gland allows nonswimming larvae to adhere to various substrates. Its secretory cells differentiate by 12 hours postfertilization and begin to disappear in the second week of life. Exogenous retinoic acid disrupts the gland's patterning. More importantly, the single mature gland emerges from fusion of two differentiated secretory cells fields; this fusion is dependent on nonmuscle myosin II function.
Taken together, our studies provide the first documentation of the embryonic development, structure, and function of the adhesive apparatus of a danioninae. To our knowledge, this is also the first report of a cement gland arising from convergence of two bilateral fields.
几个进化枝的水生物种都拥有产生不同强度粘性分泌物的黏着腺。在脊椎动物中，粘性附器在非洲爪蟾、其他无尾目动物和几种鱼类中被广泛研究。然而，这些结构的发育还不完全清楚。
在这里，我们报告了巨丹鱼物种（Devario malabaricus）的黏着腺的发育和功能形态。我们发现，该腺位于幼虫头部，由杯状分泌细胞组成，由基底细胞、边缘细胞和中间细胞框定，并由三叉神经节支配。该腺使不能游泳的幼虫能够附着在各种基质上。其分泌细胞在受精后 12 小时开始分化，并在生命的第二周开始消失。外源性视黄酸会破坏腺的模式形成。更重要的是，一个成熟的黏着腺是由两个分化的分泌细胞场融合而成的；这种融合依赖于非肌肉肌球蛋白 II 的功能。
总之，我们的研究首次提供了丹鳍鱼科黏附器的胚胎发育、结构和功能的证据。据我们所知，这也是首次报道的由两个双侧场融合形成的黏着腺。
