A FREEZE-FRACTURE STUDY OF THE PAPILLARY LAYER OF THE RAT INCISOR ENAMEL ORGAN
A FREEZE-FRACTURE STUDY OF THE PAPILLARY LAYER OF THE RAT INCISOR ENAMEL ORGAN
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DOI：
10.1016/0040-8166(84)90037-5
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发表时间：
1984-01-01
期刊：
影响因子：
2.6
通讯作者：
CHO, MI
中科院分区：
文献类型：
--
作者：
GARANT, PR;NAGY, AR;CHO, MI
牙釉质分泌后，它经历成熟或硬化。这一过程由皱褶和末端光滑的成釉细胞以及相关的乳头层细胞介导。乳头层细胞的特征是大量的线粒体、包被小泡、微绒毛和间隙连接。这些特征使许多研究者推测乳头层是一种离子转运上皮。为了更好地表征这些细胞的表面特征，对大鼠乳头层进行了冷冻断裂研究。乳头状细胞的细胞膜含有大量的膜内颗粒，其直径范围为4-9 nm。缝隙连接以环状缝隙连接的形式存在于细胞表面和细胞质中。两种类型的间隙连接的膜内颗粒或连接子均为8-9 nm宽，并且随机堆积或以所谓的结晶状态存在。在光滑端的成釉细胞和乳头层细胞之间的界面处，沿成釉细胞的基底表面存在沿着发育良好的闭合小带，并且两种细胞类型之间形成几个大的缝隙连接。与乳头层相关的毛细血管网络的特征在于含有大量开窗的薄内皮。
After tooth enamel was secreted it undergoes maturation or hardening. This process is mediated by ruffled and smooth-ended ameloblasts, and associated papillary layer cells. The cells of the papillary layer are characterized by large numbers of mitochondria, coated vesicles, microvilli and gap junctions. These features led numerous investigators to speculate that the papillary layer is an ion-transporting epithelium. Freeze-fracture studies were conducted of the rat papillary layer in order to better characterize the surface features of these cells. The cell membranes of the papillary cells contained large numbers of intramembrane particles of various sizes ranging from 4-9 nm in diameter. Gap junctions were present at the cell surface and in the cytoplasm in the form of annular gap junctions. The intramembrane particles or connexons of both types of gap junctions were .apprx. 8-9 nm wide, and were either packed randomly or present in the so-called crystallized state. At the interface between smooth-ended ameloblasts and papillary layer cells, a well developed zonula occludens was present along the basal surfaces of the ameloblasts, and several large gap junctions were formed between the 2 cell types. The capillary network associated with the papillary layer was characterized by a thin endothelium containing large numbers of fenestrations.