Teixeira C C
Department of Orthodontics, University of Pennsylvania, School of Dental Medicine, Philadelphia 19104-6003, USA.
Clin Orthod Res. 1999 Aug;2(3):171-4. doi: 10.1111/ocr.1999.2.3.171.
Information on the mechanism that governs tooth shape, size, and location in the developing jaw is sparse. One hypothesis holds that exogenous signals from the ectomesenchyme and epithelium of the embryonic jaw induce a specific pattern of cellular development that leads to tooth formation. A second hypothesis is that a specific tooth type develops from select clones of cells. The objective of this review is to consider these ideas in light of recent studies on genes that regulate embryonic patterning. Special attention is directed at the notion that there is restricted expression of specialized genes. These genes are expressed in overlapping domains along the jaw axis. Genes expressed within a region provide a unique homeobox code that serves to specify a tooth type and ultimately determines tooth form and position in the developing jaw. Expression of this genetic 'bar code' is carefully controlled by the dental epithelium, neural crest-derived cells, and growth factors. The latter agents also probably serve as epithelial signals that activate events that lead to odontogenic differentiation and morphogenesis.
关于发育中的颌骨中控制牙齿形状、大小和位置的机制的信息很少。一种假说是，来自胚胎颌骨外胚间充质和上皮的外源性信号诱导特定的细胞发育模式，从而导致牙齿形成。另一种假说是，特定的牙齿类型由选定的细胞克隆发育而来。本综述的目的是根据最近关于调节胚胎模式形成的基因的研究来考虑这些观点。特别关注的是这样一种观点，即特定基因存在限制性表达。这些基因沿着颌骨轴在重叠区域表达。在一个区域内表达的基因提供了一个独特的同源框编码，用于指定牙齿类型，并最终决定发育中的颌骨中牙齿的形态和位置。这种遗传“条形码”的表达受到牙上皮、神经嵴衍生细胞和生长因子的严格控制。后一种因子也可能作为上皮信号，激活导致牙源性分化和形态发生的事件。
