Ultrastructure of differentiating preameloblasts from tooth germs of the permanent dentition of Macaca mulatta and Macaca arctoides.
Ultrastructure of differentiating preameloblasts from tooth germs of the permanent dentition of Macaca mulatta and Macaca arctoides.
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区分猕猴和猕猴恒牙列前成釉细胞与牙胚的超微结构。
DOI：
10.1007/bf02409498
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发表时间：
1981
影响因子：
4.2
通讯作者：
Prostak,K
中科院分区：
文献类型：
--
作者：
Skobe,Z;Stern,D;Prostak,K
对两个猕猴物种的内釉质上皮和邻近结缔组织从宫颈环尖端到釉质形成开始的细胞分化进行了检查。通过灌注固定十至十二个月大的标本，并准备恒牙芽用于透射电子显微镜检查。在宫颈环本身，内釉质上皮细胞具有分叶核、缺乏细胞质和宽阔的细胞外空间；随着距颈环尖端距离的增加，逐渐发生以下变化：（a）前成釉细胞从15μm伸长至45μm，其细胞器，特别是线粒体和粗面内质网轮廓变得更多； (b) 前成釉细胞之间的细胞外空间从基底（核下）端开始减少； (c) 基底膜变得卷曲并与非周期性纤维相连； (d) 前成牙本质细胞投射穿透非周期性纤维； (e) 基底膜下方的胶原纤维密度增加，特别粗的纤维与非周期性纤维平行。这些修饰发生在从颈环尖端到矿化前沿的四分之三距离内。前成牙本质细胞的凝结之后立即进行前牙本质合成。与此同时，基底膜破裂，非周期性纤维被前成釉细胞吞噬。前成釉细胞投射穿透交界前牙本质，接触矿化牙本质，随后发生牙釉质合成。在这个阶段，成釉细胞长 45 µm，细胞核位于中央或基底，高尔基体已向顶端迁移，但 Tomes 突尚未形成。结果表明，猕猴的牙发育比鼠科啮齿动物的牙发育更接近人类的牙发育。
Cytodifferentiation of inner enamel epithelium and the adjacent connective tissue from the tip of the cervical loop to the initiation of enamel elaboration in twoMacacaspecies was examined. Ten- to twelve-month-old specimens were fixed by perfusion and the permanent tooth buds were prepared for transmission electron microscopy. At the cervical loop proper, inner enamel epithelium cells have lobed nuclei, a paucity of cytoplasm, and wide extracellular spaces; the basal lamina facing the dental papilla is straight.With increasing distance from the tip of the cervical loop, the following changes occur gradually: (a) preameloblasts elongate from 15 to 45 µm, and their organelles, particularly mitochondria and profiles of rough endoplasmic reticulum, become more numerous; (b) extracellular spaces decrease between preameloblasts starting at the basal (infranuclear) end; (c) the basement membrane becomes convoluted and associated with aperiodic fibers; (d) preodontoblast projections penetrate the aperiodic fibers; (e) collagen fibers subjacent to the basement membrane increase in density, with particularly thick fibers paralleling the aperiodic fibers. These modifications occur within three-fourths of the distance from the tip of the cervical loop to the mineralization front.The condensation of preodontoblasts is followed immediately by predentin synthesis. Concomitantly, the basement membrane breaks down and the aperiodic fibers are engulfed by preameloblasts. Preameloblast projections penetrate junctional predentin, contact mineralized dentin, and enamel synthesis ensues. At this stage the ameloblast is 45 µm long, the nucleus is central or basal, the Golgi apparatus has migrated apically, but the Tomes' process has not yet formed.The results indicate that odontogenesis inMacacamonkeys more closely resembles human odontogenesis than does that in the murine rodents.