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Histochemical and ultrastructural characterization of silk glands in larval caddisflies Insecta, Trichoptera

Larvae of Cheumatopsyche analis and Hydropsyche betteni produce a water soluable silk fiber in an aquatic environment. Study of the morpholocial characteristics of the silk gland cells would provide valuable information of where the components of the fiber and associated adhesive secretions are produced and preliminary data on their chemical composition. The silk glands of Cheumatopsyche analis and Hydropsyche betteni were examined with specific histochemical stains for lipids, proteins, nucleic acids, mucopolysaccharides and carbohydrates. Whole mounts indicate a high degree of polymorphism of the nuclei throughout the gland. In both Cheumatopsyche analis and Hydropsyche betteni typical cellular organelles, invaginating plasma membranes and microvilli are present. Serial sections indicate immediate deposit of both fiber and adhesive secretions beginning at the blind end of the gland and continues proximally through the "manufacturing" portion to the "excretory" portion.The highly proteinaceous fiber demonstrates a lack of acid mucopolysaccharides and a prevalance of carbohydrates and some polymers containing glucose, galactose and/or glucosamine. The adhesive secretion in the "manufacturing" portion is a homogenous layer surrounding the fiber. It is comprized of large amounts of carbohydrates, mucopolysaccharides and a small amount of glycoprotein which increases slightly as it followed proximally. Light staining vacuoles of similar characteristics to the fiber punctuate the coating adhesive layer and to be continuous with the fiber. In the "excretory" portion the coating adhesive layer is not found. Fiber staining intensifies greatly and similar characteristics of the adhesive section are assumed by the fiber. Cells of this portion have long microvilli and demonstrate bands of carbohydrate and mucopolysaccharides within the cytoplasm. Possible material absorbtion is indicated.Ball State UniversityMuncie, IN 47306

Identiferoai:union.ndltd.org:BSU/oai:cardinalscholar.bsu.edu:handle/181237
Date03 June 2011
CreatorsPerry, Michael Gleason
ContributorsEngstrom, Lee E.
Source SetsBall State University
Detected LanguageEnglish
Formatix, 63 leaves : ill. ; 28 cm.
SourceVirtual Press

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