In vertebrates , there are 3 main types of cell junctions.a) TIGHT JUNCTIONS help to stop substances from leaking across a tissue. Tight junctions seal adjacent epithelial cells in a narrow band just beneath their apical surface .They limit the passage of molecules and ions through the space between the cells. b) ADHERING JUNCTIONS perform cementing to keep neighbouring cells together.c) GAP JUNCTIONS ( communicating junctions,) they directly connect the cytoplasm of the two cells , which allows various Molecules ,ions and electrical impulses to directly pass through a regulated gate between cells.