(a) A section of a nurse bee head in Apis cerana showing the location of the hypopharyngeal gland located beside the compound eye and close to the mandibular gland (40x)
(b) A section of the hypopharyngeal gland of pupa of Apis cerana worker showing the incomplete irregular shaped secretory units (1000x)
(c) The micrograph illustrates the secretory units of the complete hypopharyngeal gland of A. cerana nurse bee, the cytoplasm containing a large amount of proteins is characterized by staining purple-pink color with NHS (200x)
(d) The micrograph has been stained by a histochemical method NHS to demonstrate the presence of proteins which are stained magenta to purple pink in the secretory cells of the glands of A. mellifera nurse bee (200x)
(e) A micrograph showing the histochemical appearance of the secretory units of the complete developed gland of an A. cerana guard; the cytoplasm is stained pink with NHS technique showing the narrow extracellular space between adjacent acinar cells seen by white color separating them from each other (100x)
(f) A histochemical micrograph of an A. mellifera forager showing the cytoplasm of the secretory cell seen to contain a variable numbers of secretory vesicles that are almost unstained with NHS (100x)