Tight junction (TJ) is one of the cell-cell junctions and known to have the barrier and fence functions between adjacent cells in both simple and stratified epithelia. We examined the distribution pattern, constitutive proteins, and permeability of TJ in the stratified squamous epithelium of the palatal mucosa of mice. Ultrastructural observations based on the ultrathin section and freeze-fracture methods revealed that poorly developed TJs are located at the upper layer of the stratum granulosum. The positive immunofluorescence of occludin (OCD), claudin (CLD)-1 and -4 were localized among the upper layer of the stratum granulosum showing a dot-like distribution pattern. And CLD-1 and -4 were localized among the stratum spinosum and the lower part of stratum granulosum additionally showed a positive reaction along the cell profiles. Western blotting of TJ constitutive proteins showed OCD, CLD-1, -2, -4, and -5 bands. The permeability test using biotin as a tracer revealed both the areas where biotin passed through beyond OCD positive points and the areas where biotin stopped at OCD positive points. These results show that poor TJs localize at the upper layer of the stratum granulosum of the palatal epithelium, and the TJs are leaky and include at least CLD-1 and -4.

中文翻译：

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小鼠the上皮中紧密连接的形态和功能分析。

紧密连接（TJ）是细胞-细胞连接之一，已知在简单和分层上皮中相邻细胞之间具有屏障和围栏功能。我们检查了小鼠J骨粘膜的分层鳞状上皮中TJ的分布模式，组成蛋白和通透性。基于超薄切片和冷冻断裂方法的超微结构观察表明，发育不良的TJ位于颗粒层的上层。occludin（OCD），claudin（CLD）-1和-4的阳性免疫荧光定位在颗粒层的上层之间，呈点状分布模式。并且CLD-1和-4定位在棘层中，并且颗粒层的下部沿细胞分布另外显示出阳性反应。TJ组成蛋白的蛋白质印迹显示OCD，CLD-1，-2，-4和-5条带。使用生物素作为示踪剂的渗透性测试显示了生物素穿过OCD阳性点以外的区域以及生物素在OCD阳性点处停止的区域。这些结果表明不良的TJ位于the上皮颗粒层的上层，并且TJ是渗漏的并且至少包括CLD-1和-4。