The terminal bar (arrow), visualized as dark spots that punctuate the
terminal web at the point where two cells touch at their apical margins, marks
the location of the apical junctional complex. This complex consists of the
zonula occludens junction, which forms a water tight seal around the apex
of the columnar epithelial cells and the zonula adheres junction, which attaches
adjacent cells firmly together. The zonula adherens junction is reinforced
by a band of actin microfilaments located on the cytoplasmic face of the plasma
membrane.
