Huysseune Ann
Biology Department, Ghent University, Belgium.
Int J Dev Biol. 2006;50(7):637-43. doi: 10.1387/ijdb.052098ah.
In order to test whether the formation of a replacement tooth bud in a continuously replacing dentition is linked to the functional state of the tooth predecessor, I examined the timing of development of replacement teeth with respect to their functional predecessors in the pharyngeal dentition of the zebrafish. Observations based on serial semithin sections of ten specimens, ranging in age from four week old juveniles to adults, indicate that (i) a replacement tooth germ develops at the distal end of an epithelial structure, called the successional dental lamina, budding off from the crypt epithelium surrounding the erupted part of a functional tooth; (ii) there appears to be a developmental link between the eruption of a tooth and the formation of a successional dental lamina and (iii) there can be a time difference between successional lamina formation and initiation of the new tooth germ, i.e., the successional dental lamina can remain quiescent for some time. The data suggest that the formation of a successional lamina and the differentiation of a replacement tooth germ from this lamina, are two distinct phases of a process and possibly under a different control. The strong spatio-temporal coincidence of eruption of a tooth and development of a successional dental lamina is seen as evidence for a local control over tooth replacement.
为了测试在不断更替的牙列中替换牙胚的形成是否与牙前驱体的功能状态相关，我研究了斑马鱼咽牙列中替换牙相对于其功能前驱体的发育时间。基于对10个标本（年龄从4周龄幼鱼到成鱼）的连续半薄切片观察表明：（i）替换牙胚在一种上皮结构的远端发育，这种上皮结构称为继承性牙板，它从围绕功能牙萌出部分的隐窝上皮中长出；（ii）牙齿萌出与继承性牙板的形成之间似乎存在发育联系；（iii）继承性牙板形成与新牙胚起始之间可能存在时间差异，即继承性牙板可能会静止一段时间。数据表明，继承性牙板的形成以及从该牙板分化出替换牙胚是一个过程的两个不同阶段，可能受不同控制。牙齿萌出与继承性牙板发育在时空上的强烈巧合被视为对牙齿替换进行局部控制的证据。
