A histochemical study of the hypopharangeal glands of the dwarf honey bees Apis andreniformis and Apis florea

Abstract

SummaryThe structure of the hypopharyngeal glands of Apis andreniformis and Apis florea workers was studied. Glands from pupae, nurse bees and foraging bees were investigated using paraffin and staining techniques. Periodic Acid Schiff's reagent (PAS) and Ninhydrin Schiffs reagent were used for the histochemical study of carbohydrates and proteins respectively. The glands of the two bee species were found to be quite similar in terms of histochemical structures, but differences were found between the three life stages. Pupae showed an incomplete glandular structure which was irregular in shape. Each secretory unit was composed of two to eight aggregated oval to cuboidal secretory cells with lenticular and abundant euchromatin nuclei. Weak staining with PAS and Ninhydrin Schiff's reagent indicated that the glands contained small amounts of carbohydrates and proteins. In nurse and foraging bees, however, each secretory unit was completely developed, and consisted of four to eight aggregated secretory cells with numerous large secretory vesicles. Each secretory cell was pyramidal in shape and stained strongly with both PAS and Ninhydrin Schiff's reagent, indicating that these glands were producing abundant carbohydrates and proteins, which then accumulate within the secretory vesicles. The plasma membrane between adjacent secretory cells in the secretory unit of foraging bees showed wider extracellular space than those of the nurse bees.