CELL SURFACE STUDIES OF THE ENAMEL ORGAN

现在已经确定，釉质器官具有两个主要阶段， 活动：基质生产和熟化。 细胞结构的差异 在分泌和分泌后成釉细胞、中间层和 乳头状细胞是每个阶段的特征。 分泌后 釉质器具有许多在运输中常见的特征， 上皮细胞 其中包括增加的表面积，广泛的联系型 连接，增加胞饮作用并增加线粒体数量。 它 最近已经表明，成熟（分泌后）成釉细胞 经历周期性的变化，从皱褶端细胞到光滑端细胞， 与釉质表面接触。 这些变化涉及广泛的 膜重组和细胞与细胞接触的重塑 间隙和紧密连接的变化。 在本申请中，首席仲裁员建议审查 细胞表面的分泌和分泌后釉器官， 透射电镜，冷冻断裂法，细胞化学 和放射自显影。 研究的主要重点将是获得 更好地了解釉质内的区域膜特化 并将这些器官的发育和/或退化 与釉质器官功能相关的专业化。 初探 目标是研究间隙和小带的存在和范围 在釉质器官活动的每个阶段， 冷冻断裂技术，研究分布和浓度 在各种细胞类型的膜内颗粒，以定位膜 Na-K-ATP酶的细胞化学和3 H-哇巴因结合，以研究 膜循环，包括釉质器官中的包被囊泡功能， 并研究膜甾醇分布与菲律宾结合 细胞化学 这些研究将在釉质器官上进行， 正在发育的大鼠和小鼠的门牙。 其他合适的模型，如 一些鱼类的牙釉质器官将被用来回答特定的问题。 该提案提出了一个假设，即分泌后的釉质器官 产生局部渗透梯度，需要去除水和溶质， 搪瓷。 细胞膜的结构和功能是其关键特征， 假设。 研究目标是针对这一点制定的。 假说.

It is now well established that the enamel organ has two major phases of activity: matrix production and maturation. Differences in cell structure between secretory and post-secretory ameloblasts, stratum intermedium and papillary cells, are characteristic of each phase. The post-secretory enamel organ possesses many features that are usually found in transport epithelia. Among these are increased surface area, extensive nexus-type junctions, increased pinocytosis and increases numbers of mitochondria. It has been shown recently that the maturation (post-secretory) ameloblasts undergo cyclic change from ruffle-ended to smooth-ended cells at their interface with the enamel surface. These changes involve extensive membrane reorganization and the remodeling of cell-to-cell contacts of the gap and tight junction variety. In this application the principal investigatator proposes to examine the cell surfaces of the secretory and post-secretory enamel organ by transmission electron microscopy, freeze-fracture methods, cytochemistry and autoradiography. The major focus of the research will be to gain a better understanding of regional membrane specializations within the enamel organ and to correlate the development and/or regression of these specializations with enamel organ function. The primary research objectives will be to study the presence and extent of gap and zonula occlaudens junctions at each phase of enamel organ activity by freeze-fracture techniques, to study the distribution and concentration of intramembrane particles in the various cell types, to localize membrane Na-K-ATPase by both cytochemistry and 3H-ouabain binding, to investigate membrane cycling, including coated vesicle function in the enamel organ, and to study membrane sterol distribution with filipin binding cytochemistry. These studies will be carried out on the enamel organ of continuously developing incisors of rats and mice. Other appropriate models such as the enamel organs of certain fishes will be used to answer specific questions. The proposal sets forth the hypothesis that the post-secretory enamel organ produces local osmotic gradients needed to remove water and solutes from the enamel. Cell membrane structure and function are the key features of the hypothesis. The research objectives are developed in relation to this hypothesis.