Sharks and rays (elasmobranchs) have the remarkable capacity to continuously regenerate their teeth. The polyphyodont system is considered the ancestral condition of the gnathostome dentition. Despite this shared regenerative ability, sharks and rays exhibit dramatic interspecific variation in their tooth morphology. Ray (batoidea) teeth typically constitute crushing pads of flattened teeth, whereas shark teeth are pointed, multi-cuspid units. Although recent research has addressed the molecular development of the shark dentition, little is known about that of the ray. Furthermore, how dental diversity within the elasmobranch lineage is achieved remains unknown. Here, we examine dental development and regeneration in two Batoid species: the thornback skate (Raja clavata) and the little skate (Leucoraja erinacea). Using in situ hybridization and immunohistochemistry, we examine the expression of a core gnathostome dental gene set during early development of the skate dentition and compare it to development in the shark. Elasmobranch tooth development is highly conserved, with sox2 likely playing an important role in the initiation and regeneration of teeth. Alterations to conserved genes expressed in an enamel knot-like signalling centre may explain the morphological diversity of elasmobranch teeth, thereby enabling sharks and rays to occupy diverse dietary and ecological niches.

鲨鱼和rays鱼（弹性支）具有不断再生牙齿的卓越能力。多植物牙突系统被认为是长舌宿主齿系的祖先条件。尽管具有这种共同的再生能力，但鲨鱼和rays鱼的牙齿形态仍表现出种间差异。雷（batoidea）牙齿通常构成扁平牙齿的破碎垫，而鲨鱼牙齿则是尖的多尖齿单位。尽管最近的研究已经解决了鲨鱼牙列的分子发育问题，但对射线的了解却很少。此外，如何在弹支支系内实现牙齿多样性仍然未知。在这里，我们研究了两种Batoid物种的牙齿发育和再生：棘背溜冰鞋（Raja clavata）和小溜冰鞋（Leucoraja erinacea）。使用原位杂交和免疫组织化学，我们检查了滑行牙列早期发育过程中核心gnathostome牙齿基因组的表达，并将其与鲨鱼的发育进行了比较。弹性分支牙齿的发育高度保守，sox2可能在牙齿的萌发和再生中起重要作用。在牙釉质结状信号中心表达的保守基因的改变可能解释了弹性分支牙齿的形态多样性，从而使鲨鱼和and鱼能够占据各种饮食和生态位。