We investigated the morphology and ultrastructure of the mucus glands of Apis mellifera drones, which represent a peculiar type of male accessory gland. The three different parts of the mucus glands ( muscle layer, gland epithelium and lumen) change with respect to age in the distal and the proximal parts. The thickness of musculature and gland epithelium is larger at the proximal part than at the distal part, where the diameter of the lumen is larger. The secretory cells of the epithelium reach their maximum activity during the first days of adult life, which results in a maximally filled gland lumen by the age of 6 days. The mucus glands represent a unique situation as they are of mesodermal origin, whereas the majority of exocrine glands are ectodermal.