Fang Zheng, Atukorallaya Devi
Department of Oral Biology, Rady Faculty of Health Sciences, Dr Gerald Niznick College of Dentistry, University of Manitoba, Winnipeg, Manitoba, Canada.
Anat Histol Embryol. 2025 May;54(3):e70038. doi: 10.1111/ahe.70038.
There are two main subforms of the teleost fish Mexican tetra (Astyanax mexicanus): the river-dwelling surface fish and the cave-dwelling blind cavefish. Recently, this species has become a popular animal model in developmental biology research. It was reported that cavefish bore more teeth than surface fish; however, a detailed description of oral dentition development and replacement in the Mexican tetra remains unavailable. In this study, we investigated the differences in tooth count between surface fish and cavefish by characterising the features of mandibular dentition in adult Mexican tetras and explored the process of first-generation dentition development in larval fish. Regarding early dentition development, larval surface fish and Pachón cavefish at 12-, 18-, 21-, 24-, and 30-days post-fertilisation were euthanised. Haematoxylin and eosin staining was performed for histological analysis, and immunohistochemistry was employed to detect the expression of the odontogenic marker Sox2. The results show that Mexican tetras replaced functional teeth via the successional dental lamina marked by Sox2 expression. Adult Pachón cavefish possessed more intraosseous replacement teeth. Mandibular tooth development in larval fish was also marked by Sox2 expression, and no evidence supported tooth development in a continual dental lamina. Our findings describe the appearance of a successional dental lamina in tooth replacement in the Mexican tetra but provide no evidence regarding a continual dental lamina. In the Mexican tetra, teeth of the first-generation dentition may develop independently. The results of this project will offer valuable histological information for future research into tooth development in the Mexican tetra.
硬骨鱼墨西哥丽脂鲤（Astyanax mexicanus）有两种主要的亚形态：栖息于河流的表层鱼和栖息于洞穴的盲眼洞穴鱼。最近，该物种已成为发育生物学研究中一种受欢迎的动物模型。据报道，洞穴鱼的牙齿比表层鱼多；然而，关于墨西哥丽脂鲤口腔牙列发育和替换的详细描述仍然缺乏。在本研究中，我们通过描述成年墨西哥丽脂鲤下颌牙列的特征，研究了表层鱼和洞穴鱼在牙齿数量上的差异，并探索了幼鱼第一代牙列的发育过程。关于早期牙列发育，对受精后12、18、21、24和30天的幼体表层鱼和帕琼洞穴鱼实施安乐死。进行苏木精和伊红染色以进行组织学分析，并采用免疫组织化学检测牙源性标志物Sox2的表达。结果表明，墨西哥丽脂鲤通过以Sox2表达为标记的继承性牙板替换功能性牙齿。成年帕琼洞穴鱼拥有更多的骨内替换牙。幼鱼下颌牙齿的发育也以Sox2表达为标记，并且没有证据支持在连续牙板中牙齿的发育。我们的研究结果描述了墨西哥丽脂鲤牙齿替换中继承性牙板的出现，但没有提供关于连续牙板的证据。在墨西哥丽脂鲤中，第一代牙列的牙齿可能独立发育。该项目的结果将为未来墨西哥丽脂鲤牙齿发育的研究提供有价值的组织学信息。
