PERITROPHIC MEMBRANE-STRUCTURE AND SECRETION IN EUROPEAN CORN-BORER LARVAE (OSTRINIA-NUBILALIS)

Peritrophic membrane (PM) secretion and formation occur primarily in t he anterior region of the mesenteron in the European corn borer (Ostri nia nubilalis) as determined by light and electron microscopy, Nascent PM first became visible as fibrous linear chitin-containing structure s stained with gold-labeled wheat germ agglutinin between and at the t ips of the microvilli. No formed PM was visible at the foregut-midgut junction, but a thin single PM appeared first in the lumen between the stomodeal valves and the midgut epithelium. Just posterior to the sto modeal valves, multiple PMs were observed that became progressively th icker and more numerous in the mid and posterior regions of the mesent eron, The PM consists of an orthogonal chitin meshwork with openings s lightly larger than the diameters of the microvilli. As it delaminates from the microvilli, the meshwork becomes embedded in proteinaceous m atrix that greatly reduces the pore size of the PM.