(a) High-resolution micrograph of the A. cerana nurse bee hypopharyngeal gland stained pink-purple surrounding the secretory vesicles (1000x)
(b) A section of the hypopharyngeal gland of an A. mellifera worker nurse bee showing the cytoplasm of the secretory cell containing a variable number of secretory vesicles which is stained red-pink with PAS. The oval nucleus stains pale greenish with light green (1000x)
(c) A medial section of the completely developed acinar gland of A. cerana nurse bee showing a cluster of several secretory units. The secretory cell cytoplasm is stained pink with PAS and the cell has a large nucleus. (100x)
(d) The secretory units of the hypopharyngeal gland of A. mellifera forager showing the smaller size of secretory vesicles containing less carbohydrate. These are characterized by staining slightly red-pink with PAS and showing the wide extracellular space between adjacent acinar cells which is seen by white color separating it from the other secretory cells (100x)
(e) With a higher magnification of A. mellifera guard, the secretory cell contains various sizes of secretory vesicles which are less stained to PAS than that of nurse bee (200x)
(f) A medial section of the hypopharyngeal gland of an A. cerana guard showing the shrinkage and damaged plasma membrane (400x)
