-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. morphology / mucus gland / Apis mellifera / drone

Abstract. The present study documents the pace of accessory gland and testes degeneration in the wasp Vespula vulgaris by means of a histological and metric approach, that has not been carried out for social wasps so far. To a certain extent, comparison is made with the degenerative processes of the mucus glands of the honeybee drone. In V. vulgaris, no generative tissue is left by the end of 9 d of age, and so degeneration is a fast process. The three different parts of the accessory glands (muscle layer, gland epithelium, and lumen) change with respect to age. 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 9 d. We also provide, for the first time, a histological study of testes degeneration for this species. At eclosion, well-defined cystic structures are still visible, whereas at 9 d, it is no longer possible to distinguish different cystic structures. The diameter of the testes decreases with respect to age.

We investigated the age-dependent morphology and ultrastructure of the cornua glands in drones of Apis mellifera. Two epithelial types could be distinguished, each corresponding with a different type of cuticle. The thickness of both epithelia decreases during the period of sexual maturation. Ultrastructural research did not reveal a difference between the two epithelia. morphology / cornua glands / Apis mellifera / drones

International audienceThe bulbus is a part of the unique functional penis (endophallus) in the genus Apis and was studied in Apis mellifera drones. The bulbus consists of a thin cuticular membrane, covered by four different epithelia (dorsal epithelium, anterior epithelium, ventral epithelium I and ventral epithelium II). One day before eclosion, pupae have no sclerotised plates in the bulbus lumen. In emerging drones, however, the lumen contains tanned plate-like structures, the chitin plates, subjacent are small droplets. The chitin plates are connected to each other by a transparent matrix. They consist of globular sclerotized structures which are connected by a network of fibrils. In young adult drones, the dorsal and lateral epithelia consist of highly columnar gland cells which decrease in thickness from the age of 6-12 days from 140 to 20 μm. The ultrastructural analysis combined with histochemistry shows that the gland cells secrete proteinaceous droplets towards the lumen which pass through the cuticle and the pores of the chitin plates and accumulate in the matrix. In sexually mature drones, all secretions have merged to a rigid connective substance, which extends laterally as a thin tapering membrane. The ventral epithelia I and II have no secretory function. The ventral epithelium II has a mucus-like content and several invaginations towards the lumen of the bulbus which enables widening of the bulbus orifice to discharge the bulbus secretions filled with viscous mucus via the cervix into the queen during the mating process

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