Cells of the epithelium are actually "welded" to one another through these junctions called tight junctions.

上皮细胞通过称为紧密连接的胞间连接,"焊接"在一起

耶鲁公开课 - 生物医学工程探索课程节选

That's how tight the junctions are, not even a small molecule like glucose can pass between them.

可见胞间连接多么紧密,甚至像葡萄糖这样小的分子也不能通过

耶鲁公开课 - 生物医学工程探索课程节选