Tight Junction-Zonula Occludens

The two outer lamina of the plasma membrane from two neighboring cells fuse at the zonula occludens and form abar-like, occluding junction. At the point of fusion, the whole connecting membrane is only about 15 nm thick .  There are three different types of tight junction. In this case, it is a continuous belt-type tight junction at the apicolateral plasma membrane from a jejunal enterocyte. The junction is part of the terminal web. In the PF freeze-fracture plane, the zonula occludens usually consists of a web-like lattice system . The intercellular space is occluded and the tight junction completely impermeable to hydrophilic molecules, such as ions, digestive enzymes and carbohydrates.

1 Microvilli

Electron microscopy; magnification: × 36 000

References

Kuehnel, W.(2003). Color Atlas of Cytology, Histology, and Microscopic Anatomy. 4^th edition . Institute of Anatomy Universitätzu Luebeck Luebeck, Germany . Thieme Stuttgar t · New York .