|Cicero, Joseph -|
Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 23, 2010
Publication Date: November 20, 2010
Citation: Sammataro, D., Cicero, J.M. 2010. Functional morphology of the honey stomach wall of European honey bees (Apis mellifera L.). Annals of the Entomological Society of America. 103(6):979-987. Interpretive Summary: We examined the structure of the honey stomach (or crop) of the honey bee using the Scanning Electron Microscope (SEM). This is the first time that this organ has been viewed using SEM, and the complexity of the structure was revisited since first described by early anatomists. The crop is surrounded by muscles that help to confine the underlying tissues which are pleated to form and expand as the crop is filled with nectar. During engorgement with nectar, the muscular enclosure relaxes to larger and larger diameters. Correspondingly, pleats unfold and flatten out as needed. When the nectar is expelled from the crop, the muscles contract, returning the crop to its smaller state. We also found that beneficial bacteria are living in the crop and could visualize them in the crop.
Technical Abstract: The honey bee crop, or honey stomach, is designed with cords of muscles that are numerous enough in both latitudinal and longitudinal directions to fully enclose and confine the underlying, cuticle-lines epithelium. Although appressed against the inner wall of this enclosure by the crop's contents, the epithelium is essentially free of ligations that would immobilize it. It is therefore capable of sliding on the inner wall and undergoing extensive compound pleating as needed to conform to the diameter of the enclosure regardless of the extent of contraction or distention. Further, the two primary components of the epithelial layer, epidermal cells and procuticle, are capable of undergoing extreme compression to maintain pleats while enduring the pressure exerted by the volume of crop contents. During enforcement with nectar, the muscular enclosure relaxes to larger and larger diameters. Correspondingly, pleats unfold and flatten out as needed. During dispensation of nectar in the hive, the muscular enclosure contracts and forces the epithelium to pleat itself again. Pleats are present in even the most grossly distended crops, indicating that capacity is not a limiting factor in the volume of nectar a bee can accumulate during foraging.