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Research article - Peer-reviewed, 2023

Regionalization of cell types in silk glands of Larinioides sclopetarius suggest that spider silk fibers are complex layered structures

Sonavane, Sumalata; Westermark, Per; Rising, Anna; Holm, Lena

Abstract

In order to produce artifcial silk fbers with properties that match the native spider silk we likely need to closely mimic the spinning process as well as fber architecture and composition. To increase our understanding of the structure and function of the diferent silk glands of the orb weaver Larinioides sclopetarius, we used resin sections for detailed morphology, parafn embedded sections for a variety of diferent histological stainings, and a histochemical method for localization of carbonic anhydrase activity. Our results show that all silk glands, except the tubuliform glands, are composed of two or more columnar epithelial cell types, some of which have not been described previously. We observed distinct regionalization of the cell types indicating sequential addition of secretory products during silk formation. This means that the major ampullate, minor ampullate, aciniform type II, and piriform silk fbers most likely are layered and that each layer has a specifc composition. Furthermore, a substance that stains positive for polysaccharides may be added to the silk in all glands except in the type I aciniform glands. Active carbonic anhydrase was found in all silk glands and/or ducts except in the type I aciniform and tubuliform glands, with the strongest staining in aggregate glands and their ductal nodules. Carbonic anhydrase plays an important role in the generation of a pH gradient in the major ampullate glands, and our results suggest that some other glands may also harbor pH gradients.

Published in

Scientific Reports
2023, Volume: 13, article number: 22273