- 作者：Noriyuki Saharaa ; sahara@po.mdu.ac.jp" class="auth_mail" title="E-mail the corresponding author ; Keita Moriyamab ; Midori Iidac ; Shun Watanabed
- 关键词：First functional teeth ; Upper jaw tooth ; Cranial metamorphosis ; Sicyopterus japonicus ; Gobiid fish ; Teleost
- 刊名：Archives of Oral Biology
- 出版年：2016
- 出版时间：June 2016
- 年：2016
- 卷：66
- 期：Complete
- 页码：8-14
- 全文大小：1801 K
Design
Fishes were caught at the post-larval stage at a river mouth and maintained for 7 days in a water tank. Each of 10 specimens was evaluated every day for 7 days by using microcomputed tomography, scanning electron microscopy, and light microscopy with peculiar attention to the development of the upper jaw teeth.
Results
Fishes caught at the river mouth were mostly transparent, with a rostral terminal mouth, and no teeth could be found in either the upper or lower jaw. At 2 days after collection, the mouth position changed from terminal to subterminal, resulting from a change in head shape. The initial eruption of first functional teeth was detected at the anterior two-thirds region of each upper jaw. These teeth erupted in adjacent positions, most had a tricuspid crown, and they represented miniature versions of adult teeth. At 5 days, the position of the mouth became further relocated from terminal rostral to ventral. The number of erupted teeth increased, followed by spreading of them anteriorly and posteriorly. At 7 days, they formed a single row of close-set tricuspid teeth along the entire length of each upper jaw.
Conclusions
The present study demonstrated that even under laboratory conditions a rapid and drastic cranial metamorphosis took place within a week after the time of collection of post-larval S. japonicus from a river. The eruption of first functional teeth in the upper jaw of S. japonicus, which teeth are adapted to scraping algae off the substrate, was initially detected at 2 days after collection, and first functional dentition of the upper jaw was set up within 7 days after it.