The guide structure for stoppers takes the form of a tunnel with a C-shaped section for trapping and guiding the cylindrical part of the stoppers (1c, 1t), which tunnel has opposing edges spaced out at a distance such as to allow the passage of the bulge (3) of the nipple-type stoppers (1t). This structure consists of filamentary rails (5) and of plates (6) with a hole through their central part shaped according to the profile of the stoppers that are to be transferred.