Every junction is dowelled together at two points and the holes for the dowels are drilled completely through the chipboard and then plugged both sides with little studs.  There were over 60 studs when it was finished, some making the shelves knobbly and not good for standing anything on.    lf, like me you like the configuration you can do what l did: fill all the holes with wood filler, prime it with primer suitable for melamine coated chipboard and then give it two or three coats of paint.  l ended up with something l am happy to have in my home, but if left in its original state l wouldn't give it house room.