The communication junctions in multicellular plants are called plasmodesmata. They represent small channels through the cell wall connecting the cytoplasmic contents of two neighbor cells. The inner surface of the pore in a cell wall is covered with a cellular membrane that is the extension of the cellular plasmalemma. Plasmodesmata pores may contain the desmotubule that links endoplasmic reticulums of two adjacent cells. Also, microtubules and actin filaments can be found in the channel. These structures are required for the transport of large molecules and viruses. Plasmodesmata provide the transportation of ions, small molecules, proteins, nucleic acids (RNA, viroids, etc.) and viruses mediating the communication between plant cells.