ULTRASTRUCTURAL ANALYSIS OF BONE NODULES FORMED INVITRO BY ISOLATED FETAL-RAT CALVARIA CELLS
ULTRASTRUCTURAL ANALYSIS OF BONE NODULES FORMED INVITRO BY ISOLATED FETAL-RAT CALVARIA CELLS
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DOI：
10.1016/8756-3282(88)90005-1
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发表时间：
1988-01-01
期刊：
影响因子：
4.1
通讯作者：
AUBIN, JE
中科院分区：
文献类型：
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作者：
BHARGAVA, U;BARLEV, M;AUBIN, JE
从21日龄胎鼠颅骨中酶消化的细胞在抗坏血酸和β-甘油磷酸钠中生长时，形成具有编织骨的组织学和免疫组织化学外观的离散的三维结节结构。目前的研究是为了验证骨样特征在超微结构水平上是可识别的。结节形成在成纤维细胞样的双层细胞上。结节的上表面排列着一层连续的立方形成骨细胞，通常通过粘连连接连接在一起。在这些细胞的上表面可以看到大量的微绒毛、膜突起和被覆的凹陷，它们的细胞质含有突出的RER和高尔基膜，突起从它们的下表面延伸到致密的、高度组织的胶原基质。一些成骨细胞样细胞完全包埋在基质中；它们还显示dRER和突出的突起，这些突起贯穿基质，经常与其他细胞的突起形成粘连和缝隙连接。没有参与结节形成的成纤维细胞被密度较低的胶原基质包围，与结节的基质相反，它没有矿化。在立方细胞顶层的正下方可见一层未矿化的类骨样层。在细胞的立方顶层下方可检测到矿化前沿。在其下方可检测到矿化前沿，其中类似于基质小泡和羽毛状矿物晶体的小而离散的结构明显，并且经常与胶原纤维相关联。结节内可见更多矿化较重的区域。电子探针、电子和X射线衍射分析证实该矿物为羟基磷灰石。所有观察到的超微结构特征表明，结节与真实骨相似，因此是研究体外骨形成和骨细胞分化代谢参数的良好模型。
When cells enzymatically digested from 21 d fetal rat calvaria are grown in ascorbic acid and Na .beta.-glycerophosphate, they form discrete three-dimensional nodular structures with the histological and immunohistochemical appearance of woven bone. The present investigation was undertaken to verify that bone-like features were identifiable at the ultrastructural level. The nodules formed on top of a fibroblast-like bilayer of cells. The upper surface of the nodules was lined by a continuous layer of cuboidal osteoblastic cells often seen to be joined by adherens junctions. Numerous microvilli, membrane protrusions, and coated pits could be seen on the upper surface of these cells, their cytoplasm contained prominent RER and Golgi membranes, and processes extended from their lower surfaces into a dense, highly organized collagenous matrix. Some osteocyte-like cells were completely embedded within this matrix; they also displaye dRER and prominent processes which extended through the matrix and often made both adherens and gap junctional contacts with the processes of other cells. The fibroblastic cells not participating in nodule formation were surrounded by a less dense collagenous matrix and, in contrast to the matrix of the nodules, it did not mineralize. An unmineralized osteoid-like layer was seen directly below the cuboidal top layer of cells. A mineralization front was detectable below the cuboidal top layer of cells. A mineralization front was detectable below this in which small, discrete structures resembling matrix vesicles and feathery mineral crystals were evident and frequently associated with the collagen fibrils. More heavily mineralized areas were seen further into the nodule. Electron microprobe and electron and X-ray diffraction analysis confirmed the mineral to be hydroxylapatite. All the ultrastructural features observed indicated that nodules resemble true bone and therefore are an excellent model to investigate parameters of bone formation and bone cell differentiation and metabolism in vitro.