Vainio S, Thesleff I
Department of Pedodontics and Orthodontics, University of Helsinki, Finland.
Differentiation. 1992 Jun;50(2):97-105. doi: 10.1111/j.1432-0436.1992.tb00490.x.
The cell surface proteoglycan, syndecan, and the extracellular matrix glycoprotein, tenascin, are expressed in the mesenchyme during early development of many organs. We have studied the expression patterns of syndecan and tenascin during initiation of tooth development and in association with mesenchymal cell condensation and compared these with cell proliferation. Syndecan, tenascin and bromodeoxyuridine (BrdU) incorporation were localized by triple-labelling immunohistochemistry in serial sections of molar tooth germs of mouse embryos. Prior to formation of the epithelial tooth bud, syndecan accumulated in the mesenchymal cells which underlie the presumptive dental epithelium, but tenascin was not detected at this stage. Tenascin appeared during initiation of the epithelial down-growth at the lingual aspect of the tooth germ. During subsequent formation of the epithelial bud, at the late bud stage, syndecan and tenascin became exactly colocalized in the condensed mesenchyme which was clearly demarcated from other jaw mesenchyme. The expression of syndecan and tenascin was accompanied by rapid cell proliferation as indicated by marked BrdU incorporation. When development advanced to the cap stage, syndecan staining intensity in the dental papilla mesenchyme increased further whereas tenascin became reduced. In conclusion, the results demonstrate that the expression patterns of syndecan and tenascin overlap transiently during the period of mesenchymal cell condensation and that this is accompanied by cell proliferation. Syndecan and tenascin may play a role in growth control and in compartmentalization of the dental mesenchymal cells in the condensate.
细胞表面蛋白聚糖（syndecan）和细胞外基质糖蛋白（腱生蛋白）在许多器官的早期发育过程中表达于间充质。我们研究了syndecan和腱生蛋白在牙齿发育起始阶段以及与间充质细胞凝聚相关过程中的表达模式，并将其与细胞增殖情况进行了比较。通过三重标记免疫组织化学方法，在小鼠胚胎磨牙牙胚的连续切片中对syndecan、腱生蛋白和溴脱氧尿苷（BrdU）掺入情况进行了定位。在牙上皮芽形成之前，syndecan在假定牙上皮下方的间充质细胞中积累，但在此阶段未检测到腱生蛋白。腱生蛋白在牙胚舌侧上皮向下生长起始时出现。在随后上皮芽形成过程中，即在芽后期，syndecan和腱生蛋白在凝聚的间充质中完全共定位，该凝聚间充质与其他颌间充质有明显界限。如显著的BrdU掺入所示，syndecan和腱生蛋白的表达伴随着快速的细胞增殖。当发育进入帽状期时，牙乳头间充质中syndecan染色强度进一步增加，而腱生蛋白减少。总之，结果表明syndecan和腱生蛋白的表达模式在间充质细胞凝聚期间短暂重叠，且这一过程伴随着细胞增殖。Syndecan和腱生蛋白可能在生长控制以及凝聚物中牙间充质细胞的分隔中发挥作用。
