title: Fine structure of the tegumentary glands secreting the protective "shield" in a sessile insect (Homoptera, Diaspiddae).
abstract: The tegumentary pygidial glands of Aonidiella aurantii (Homoptera, Diaspididae) produce a secretion forming the shield of these fixed parasites of plants. They are formed of seven cells: a principal unpaired secretory cell which produces an abundant glycoproteinaceous secretion; a small associated cell with a secondary reservoir for this secretion; two accessory secretory cells which have very abundant tubular extensions coming from the plasma membrane, and a flocculent secretion gathered in a large sub-cuticular space; two cells forming an enlarged part of the excretory canal, functioning like a spinneret; and finally a single cell forming the tubular duct of this complex gland. The cuticle of the secretory cells has a very special porous structure, through which the secretion passes. The final product is a ribbon formed by two hollow strands stuck together. The exact nature of this secretion is not clear. It is comparable to a silk secretion though it has its own particular characteristics.
mesh_terms: D002462:Cell Membrane / Q000648:ultrastructure; D005088:Exocrine Glands / Q000502:physiology / Q000648:ultrastructure; D006023:Glycoproteins / Q000378:metabolism; D007313:Insecta / Q000648:ultrastructure*; D009940:Organoids / Q000648:ultrastructure
chemical_list: D006023:Glycoproteins