The hypopharyngeal glands of Apis cerana workers infected with sac brood virus showed changes when compared with the glands of healthy bees: the area between the intracellular ductules and the outer membrane was greatly reduced, suggesting that royal jelly secretion was much less than in healthy bees of the same age (5 - 6 days). the glands of diseased bees showed much less endoplasmic reticulum and fewer ribosomes than the glands of helathy bees. In infected bees, remnants of mitochondria were observed in hypopharyngeal gland cells, and the mitochondria of diseased bees were sometimes transformed into large vacuoles; lysosomes were transformed into myelin-like membranes.