Ultrastructural analysis on the gland secretion in the extracellular ducts of the hypopharyngeal glands of the honeybee infected by Nosema apis

The hypopharyngeal glands of the honeybee secrete the larval food royal jelly, along with enzymes that are used in the production of honey from nectar. The composition of this secretion mixture varies with the physiological condition of the honeybee, and the final secretion mixture is conveyed through the extracellular ducts to the large excretory duct. The secretion products in the extracellular duct of both healthy and infected honeybees, was studied by transmission electron microscopy and image analysis. These products consisted of a densely packed, faintly visible granular substance. The granules were clearly defined by the computer enhanced image. The secretion products from the Nosema-infected honeybees exhibited the same granular structure, but were much less concentrated, thereby reducing the overall electron density of the secretion. These observations suggest that the composition of the secretion products from the hypopharyngeal glands in the Nosema-infected honeybees, was altered considerably.