Final answer:
Desmosomes are the primary structures responsible for binding animal cells together, acting as spot welds and providing strength to tissues.
Step-by-step explanation:
The primary role of desmosomes is to bind animal cells together. Desmosomes act like strong spot welds between cells, serving as one type of intercellular junction. They utilize cadherins to attach cells to each other, spanning the space between adjacent cell membranes. These cadherins are linked to plaque proteins within the cell, which in turn are connected to intermediate filaments of the cytoskeleton, lending robust support and stability to the tissue.
Tight junctions form watertight seals between animal cells rather than acting as mechanical attachments. On the other hand, gap junctions allow for communication between animal cells through channels but are not primarily for binding. In contrast, plasmodesmata perform a similar communication function in plant cells but are not found in animal cells.