Junctions between cells

There are three junction types I will discuss here:

1. Tight junction (aka: zonula occludens): this is a site where two cell membranes come very close together and almost seem to be fused; they, in fact, prohibit materials from going between the two cells

2. Desmosomes (aka: macula adherens): interactions of calcium ions and adhesion between cell membranes

3. Gap junction: this is when the cytoplasm of two cells are connected by a channel

Here's where I got this info...