Sahara Noriyuki, Moriyama Keita, Iida Midori, Watanabe Shun
Department of Hard Tissue Research, Graduate School of Oral Medicine, Matsumoto Dental University, Shiojiri, Nagano, Japan.
J Morphol. 2013 May;274(5):512-24. doi: 10.1002/jmor.20111. Epub 2012 Dec 27.
Sicyopterus japonicus (Teleostei, Gobiidae), a hill-stream herbivorous gobiid fish, possesses an unusual oral dentition among teleost fishes on account of its feeding habitat. By using scanning electron microscopy, light microscopy, and transmission electron microscopy, including vital staining with tetracycline, we examined the development of the attachment tissues of the upper jaw teeth in this fish. The functional teeth of S. japonicus had an asymmetrical dentine shaft. The dentine shaft attached to the underlying uniquely shaped pedicel by means of two different attachment mechanisms. At the lingual base, collagen fiber bundles connected the dentine shaft with the pedicel (hinged attachment), whereas the labial base articulated with an oval-shaped projection of the pedicel (articulate attachment). The pedicel bases were firmly ankylosed to the crest of the thin flange of porous spongy bone on the premaxillary bone, which afforded a flange-groove system on the labial surface of the premaxillary bone. Developmentally, the pedicel and thin flange of spongy bone were completely different mineralized attachment tissues. The pedicel had a dual origin, i.e., the dental papilla cells, which differentiated into odontoblasts that constructed the internal surface of the pedicel, and the mesenchymal cells, which differentiated into osteoblasts that formed the outer face of the pedicel. A thin flange of spongy bone was deposited on the superficial resorbed labial side of the premaxillary bone proper, and later rapid bone remodeling proceeded toward the pedicel base. These unique features of pedicellate tooth attachment for the upper jaw teeth in the adult S. japonicus are highly modified teeth for enhancing the ability of individual functional teeth to move closely over irregularities in the rock surfaces during the scraping of algae.
日本弹涂鱼（硬骨鱼纲，虾虎鱼科）是一种生活在山间溪流的草食性虾虎鱼，因其摄食栖息地的原因，在硬骨鱼类中拥有不同寻常的口腔齿列。我们通过扫描电子显微镜、光学显微镜和透射电子显微镜，包括用四环素进行活体染色，研究了这种鱼上颌牙齿附着组织的发育情况。日本弹涂鱼的功能牙具有不对称的牙本质轴。牙本质轴通过两种不同的附着机制与下方独特形状的蒂相连。在舌侧基部，胶原纤维束将牙本质轴与蒂相连（铰链附着），而唇侧基部则与蒂的椭圆形突起铰接（关节附着）。蒂基部牢固地融合在上颌骨上多孔海绵状骨薄凸缘的嵴上，在上颌骨唇面形成了一个凸缘 - 凹槽系统。在发育过程中，蒂和海绵状骨的薄凸缘是完全不同的矿化附着组织。蒂有双重起源，即牙乳头细胞分化为成牙本质细胞，构建了蒂的内表面，间充质细胞分化为成骨细胞，形成了蒂的外表面。上颌骨本体唇侧表面浅层吸收处沉积了一层薄的海绵状骨凸缘，随后快速的骨重塑朝着蒂基部进行。成年日本弹涂鱼上颌牙齿这种带蒂牙齿附着的独特特征是高度特化的牙齿，可增强单个功能牙在刮食藻类时紧密贴合岩石表面不规则处移动的能力。
