Fibroblast growth factor 9: cloning and immunolocalisation during tooth development in Didelphis albiventris

There are no reports in literature about functional roles of fibroblast growth factor 9 (FGF-9) in tooth development in animals with complete tooth pattern. The classical model for studying tooth development is the mouse, which has small number of teeth and distinctive incisor and molar patterns. The opossum Didelphis albiventris with five upper and four lower incisors, one canine, three premolars, and four molars, on each side of the jaw, seems to be a convenient model to test results obtained in the mouse. Molecular expression studies indicate that FGF-9 participates in murine tooth initiation and regulation of morphogenesis. Searching for similarities and differences in FGF-9 expression between the opossum and the mouse, amino acid sequence and expression pattern of FGF-9 in the developing first molars of D. albiventris were characterised. FGF-9 cDNA sequence was obtained using RT-PCR and expressed in bacterial system for recombinant protein production and analysis of immunoreactivity. FGF-9 expression during tooth development was investigated by immunoperoxidase method. FGF-9 protein consists in a 209-residue polypeptide with a predicted molecular mass of 23.5 kDa. FGF-9 amino acid sequence has 98% of sequence identity to human and 97% to rodents. During tooth development, epithelial FGF-9 expression was seen at the dental lamina stage. Mesenchymal expression was seen at the bud stage and at the cap stage. No significant expression was found in the enamel knot. While in rodents FGF-9 is involved in initiation and regulation of tooth shape, it is suggested that it is only involved in tooth initiation in D. albiventris.     

碱性成纤维细胞生长因子在人牙胚生长发育中的作用

目的 :研究碱性成纤维细胞生长因子在人牙胚生长发育中的作用。方法 :选择胎龄分别为 7、8、10、14周自愿终止妊娠的新鲜人胚胎各 4例 ,制作牙胚切片 ,将蕾状期、帽状期和钟状期牙胚切片 ,做免疫组化检测。结果 :bFGF在蕾状期上皮细胞强染 ,外胚间充质细胞少量弱染色 ;帽状期 ,bFGF在上皮细胞呈整体弱染色 ,牙乳头细胞染色更弱 ;钟状期 ,bFGF在内釉细胞呈强染色 ,牙乳头近切缘的外层细胞亦呈阳性染色 ,星网状层少量细胞弱染色。结论 :bFGF对人牙胚上皮细胞的增殖和分化起着促进作用 ;在人牙胚的钟状期 ,bFGF在促进内釉上皮细胞向成釉细胞转化以及牙乳头细胞向成牙本质细胞转化中起重要作用 ,促进牙胚发育成熟     

碱性成纤维细胞生长因子在人牙胚中表达的免疫组化定位

目的：观察碱性成纤维细胞生长因子（ｂＦＧＦ）表达与人牙胚发育和分化的关系。方法：采用免疫组化方法观察ｂＦＧＦ在人牙胚发育中的定位。结果：钟状期牙胚中前成釉细胞为ｂＦＧＦ强阳性，星网层可疑；成牙本质细胞为强阳性，牙乳头组织中阳性分布不均，靠近成牙本质细胞的牙乳头细胞为阳性；牙囊细胞阳性，血管内皮细胞呈强阳性；骨组织为阴性。结论：ｂＦＧＦ与成釉细胞、成牙本质细胞的分化和成熟有关。     

Three-dimensional mammalian tooth development using diceCT

ObjectiveThis study aims to develop the Diffusible Iodine-based Contrast-Enhanced CT (diceCT) method for non-destructive imaging of both soft and mineralised tissues. We sought to document the 3D spatio-temporal pattern of mammalian tooth development including multiple tooth classes and generations, using the tammar wallaby (Macropus eugenii) as a model species.DesignWe took microCT scans of developing fetuses and pouch young stained using Lugol’s Iodine (I₂KI) contrast agent. Stained versus unstained specimen comparisons were then made to investigate whether staining had improved visualisation of structures. Scan slices were compared to histological sections to confirm the identity of tissues and structures. Tissue layers were digitally segmented to create 3D models.ResultsDiceCT dramatically enhanced visual contrast of soft tissues, allowing differentiation between epithelial and mesenchymal layers. Subvolume scans at higher magnification achieved single-cell layer resolution within relatively large intact heads. We observed in-situ initiating teeth, which progressed through major stages of tooth development including morphogenesis and mineralisation. In addition, we traced the development of other mineralized and unmineralised tissues, such as the cranial bones and the brain, eye and olfactory system.ConclusionsDiceCT was time- and cost-effective in producing complex 3D models of the entire dentition of the tammar wallaby at each developmental stage with tissue-level resolution. The 3D view of soft and mineralised tooth structures allowed us to define tooth class and generation from a developmental perspective. Additionally, the development of other organs can also be documented using the same scans, demonstrating the efficiency and versatility of this technique.     

血管内皮生长因子与牙发生发育的关系

血管内皮生长因子（VEGF）不仅在促进血管内皮细胞分裂与增殖、胚胎发生发育、创伤愈合中发挥着重要的作用,而且在骨的生成与改建过程中,成骨细胞来源的VEGF作用于破骨细胞分化使破骨细胞发生趋化,使局部破骨细胞数目增加并促进局部骨吸收。上皮组织与外胚间叶组织的互相作用贯穿于牙胚发生发育到牙体组织形成的整个过程,内外釉上皮细胞与牙乳头细胞分泌的VEGF及其受体互相作用,促进成釉细胞与成牙本质细胞的分化成熟,影响釉质与牙本质的形成。许多与牙发生相关的基因表达于牙胚中央的釉结中,这些基因涉及的信号转导通路也参与牙的发生。VEGF基因表达受到无翅型小鼠乳房肿瘤病毒整合位点家族/β-连环蛋白信号转导通路的调控。目前,有关VEGF和VEGFR在牙胚发生发育中的认识仅仅停留在表观层面,对于功能及调控机制有待深入的研究。     

成纤维细胞生长因子在牙齿发育中的作用

牙齿在发育过程中受多种信号分子调控,成纤维细胞生长因子（fibroblast growth factors,FGFs）是具有多种生物学作用的细胞因子,它在牙齿发育的不同阶段都发挥着重要作用.本文就其在牙齿发育中的作用和调节作一综述.     

A novel approach for inhibiting growth factor signalling in murine tooth development: Inhibition of FGF's

Growth factors belonging to the FGF and TGF-β families, together with other secreted factors such as Sonic hedgehog, have been shown to be spatially and temporally regulated during tooth development. Providing evidence of the functions of these molecules has, however, proved difficult. We have developed a novel strategy for investigating the role of secreted molecules in tooth development using soluble forms of membrane bound receptors to sequester ligands. Chimeric fusion proteins of receptor extracellular domains were cloned into the eukaryotic expression vector pIG-1 and transfected into COS cells. Fusion proteins secreted by the COS cells were purified using Protein A Sepharose. A soluble form of the FGF receptor FGF-1IIIc, which preferentially binds FGF-2 and FGF-4, was produced using this technique and added to mouse mandible cultures. Addition of the soluble receptors to E13 cultures resulted in down-regulation of Sonic hedgehog expression in molar enamel knots, consistent with inhibition of FGF-4 signalling.     

碱性成纤维细胞生长因子对体外大鼠牙胚分化的影响

目的：观察外源性ｂＦＧＦ对体外培养牙胚发育和分化的作用。方法：采用体外培养１７ｄＳＤ胎鼠第一磨牙牙胚，培养液中加入１０ｎｇ／ｍｌ人重组ｂＦＧＦ（ｈｂＦＧＦ），分别培养３、６、９ｄ，组织学观察。结果：外源性ｈｂＦＧＦ可使大鼠牙胚的细胞分化和牙本质基质分泌加快。结论：外源性ｂＦＧＦ可以促进大鼠牙胚的发育，加速牙齿发育。     

bFGF对体外培养人牙囊细胞VEGF表达的影响

目的：研究碱性成纤维细胞生长因子（bFGF）对体外培养人牙囊细胞血管内皮生长因子（VEGF）表达的影响。方法：选取生长状态良好的人牙囊细胞,与10ng／mlbFGF孵育不同时间后,采用反转录聚合酶链反应（RT—PCR）及酶联免疫吸附试验（ELISA）分别检测人牙囊细胞VEGFmRNA表达及上清液中VEGF蛋白分泌变化。结果：bFGF作用1、3、6、12h后人牙囊细胞VEGFmRNA表达均较0h组显著增强（p〈0．01）,其中bFGF作用6h后VEGFmRNA表达最强;细胞培养上清液中VEGF蛋白分泌量随时间延长逐渐增加,但bFGF处理组VEGF蛋白分泌量高于对照组（p〈0．01）。结论：bFGF能够促进体外培养人牙囊细胞VEGF的表达。     

骨形态发生蛋白信号通路在牙根发育中的作用

骨形态发生蛋白（BMP）家族是调节细胞生命活动的重要因子,几乎参与了所有组织的发育。BMP介导的信号通路在牙发育过程中发挥十分重要的作用,而牙根发育是牙发育的一部分,是上皮和间充质相互作用的复杂过程。上皮和牙胚间充质中的BMP信号通路在牙根发育中的作用也有所不同,本文综述了BMP信号通路在牙根发育中作用的研究进展。     

正畸力作用下大鼠牙周组织中表皮生长因子的表达

目的 检测正畸力作用下大鼠牙周组织中表皮生长因子（epidermal growth factor,EGF)及其受体的表达与分布，探讨EGF在正畸牙移动过程中的作用及机制。方法 建立大鼠正畸牙移动模型，分别在受力24h及168h处死，制备左侧上颌第一磨牙及牙周组织的石蜡标本，采用免疫组化HI－SABC法进行检测。结果 EGF与EGFR在正畸组大鼠牙周组织中的表达明显强于对照组（P＜0.01)，受力168h组EGF及EGFR表达的强度高于受力24h组（P＜0.01)；同时间组中，张力侧EGF及EGFR的表达高于压力侧（P＜0.01)；EGF、EGFR在正畸组中的表达主要是位于近远中向的张、压力侧，而生理状态下主要位于根尖及根分叉区的牙周膜。结论 正畸牙移动过程中EGF、EGFR的表达有所增强，提示EGF可能参与了正畸牙移动，并且更多地促进了正畸牙骨改建中的骨形成过程。     

BMP 1和mTLL1在牙齿发育中的研究进展

骨形态发生蛋白1(bone morphogenetic protein 1,BMP1)和哺乳动物tolloid样1(mammalian tolloid-like 1,mTLL1)是细胞外基质金属蛋白酶,同属于虾红素家族(astacin family),在包括牙在内的多种组织中共表达.BMP1和mTLL1具有功能冗余性,...     

Dkk-Wnt信号通路在牙齿发育中作用的研究进展

哺乳动物的牙齿发育是外胚层上皮与间充质间相互调控和信号交流的结果,其中Dkk-Wnt信号通路是近年来牙胚发育研究领域的热点。Dkk-Wnt信号通路已被证实在牙体形成细胞功能的发挥、牙齿模式化、形态发生、牙冠钙化过程中扮演重要作用。牙齿发生发育分子机制的深入研究,将为牙再生组织工程技术以及相关技术的临床转化提供理论基础。本文就近十年对Wnt信号通路在牙齿发育中所起作用的研究作一综述。     

转化生长因子β信号转导与成牙本质细胞分化

转化生长因子β在牙胚发育，成牙本质细胞分化和牙髓损伤修复过程中均发挥着重要的作用，本文就TGF－β近年来的研究进展，尤其是TGF－β－Smad信号途径与成牙本质细胞分化机制的相互关系作一综述。     

大鼠正畸牙移动过程中牙周组织NGF的表达变化

目的了解大鼠正畸牙移动过程中牙周组织内神经生长因子(nerve growth factor,NGF)的变化,探讨NGF在正畸牙移动过程中的作用。方法将85只雄性SD大鼠随机分为17组,其中空白对照组(0d组)、实验加力和对照不加力组各6h、12h、24h、3d、5d、7d、14d、21d组。选择左上第一磨牙作为实验牙,制备大鼠正畸牙移动不同时间牙周组织切片,进行免疫组织化学研究。结果正畸牙移动过程中,牙周组织内NGF表达发生改变。NGF表达量在正畸模型加载后迅速上调,实验组和对照组分别于5d、1d时表达水平达到最高,所有观察区域牙周膜内NGF表达显著增加,且实验组明显高于对照组。结论NGF在正畸牙移动过程中牙周组织改建的多个阶段起作用,参与了牙周膜早期的炎症反应及修复和晚期的改建。     

Ihh signaling regulates mandibular symphysis development and growth

Symphyseal secondary cartilage is important for mandibular development, but the molecular mechanisms underlying its formation remain largely unknown. Here we asked whether Indian hedgehog (Ihh) regulates symphyseal cartilage development and growth. By embryonic days 16.5 to 18.5, Sox9-expressing chondrocytes formed within condensed Tgfβ-1/Runx2-expressing mesenchymal cells at the prospective symphyseal joint site, and established a growth-plate-like structure with distinct Ihh, collagen X, and osteopontin expression patterns. In post-natal life, mesenchymal cells expressing the Ihh receptor Patched1 were present anterior to the Ihh-expressing secondary cartilage, proliferated, differentiated into chondrocytes, and contributed to anterior growth of alveolar bone. In Ihh-null mice, however, symphyseal development was defective, mainly because of enhanced chondrocyte maturation and reduced proliferation of chondroprogenitor cells. Proliferation was partially restored in dual Ihh;Gli3 mutants, suggesting that Gli3 is normally a negative regulator of symphyseal development. Thus, Ihh signaling is essential for symphyseal cartilage development and anterior mandibular growth.