THE FINE STRUCTURE OF THE WAX GLAND OF THE HONEY BEE (APIS MELLIFERA L.)

Abstract

An electron microscopic study was initiated to elucidate the ultrastructure of the wax gland in an actively wax secreting worker honey bee. The investigation showed that the cuticle is penetrated by bundles of fibers or pores. The epithelial cells of the wax gland possess tubular invaginations filled with material which accummulates below the cuticle. The numerous mitochondria, microtubules and convolutions located in the cells suggest that this epithelium functions in either the transport or the concentration of substances during bees wax synthesis rather than storage for release associated with secretory cells. Whether the pore canals are made up of microfilaments or microtubules is still uncertain for the morphology seems to vary in different preparations depending on the fixation procedure. Our findings support the microtubule interpretation, especially since both the microtubules of the underlying epithelium and the wax filaments measure about 230 A in diameter. The microtubular structure of the wax gland cell appears to function as a cytoskeleton. Secretion of wax to protect against water loss through the integument is a common phenomenon in insects. The honey bee, in addition to this protective layer, also produces wax used in the construction of combs. Beeswax is secreted by worker bees on paired, smooth, oblong areas, called wax mirrors, located ventrally on abdominal segments four through seven. On the dorsal side of each wax mirror is a layer of epithelial tissue called the wax gland. This epithelium is seen to fluctuate in development in individual workers dictated by various factors including the age of the secreting bee, its nutritional state and the colony's need for wax production. As secretory activity increases, the cells of the wax gland become tall and slender (D REILING , 1903). Production of beeswax in the honey bee is a process whereby many thin layers of wax are deposited on the wax mirror until a scale results (D IETZ and