Age-dependent morphology and ultrastructure of the hypopharyngeal gland of Apis mellifera workers (Hymenoptera, Apidae)

Overview & Synopsis

The main secretory products of the hypopharyngeal gland are royal jelly compounds, as well as other substances such as $\alpha$-glucosidase. Our study of the morphology and ultrastructure of this gland in relation to worker's age clearly shows a secretory cycle within the cells, although production of secretion is asynchroneous between different cells within an acinus. Secretory vesicles appear already in 3 day old bees, while peak production is around 6 days. Thereafter, the volume of the acini as well as the number of secretory vesicles decrease and no vesicles are visible after 3 weeks of age. Foragers display degenerative structures in their cells. The hypopharyngeal gland cells of winter bees contain large numbers of secretory vesicles, that are probably stored until spring.