Fine structure of cribellate spider silk.

Sticky silk from webs of the spiders, Uloborus diversus and Filistata arizoniciis,were examined by election microscopy. The silk of contains long fibrils, 200 –300 A˚ in diameter, consisting of an electron-dense central filament, 30 –60 A˚ across, embedded in a lighter matrix. Transverse banding is distinguished in the matrix at intervals from over 200 to less than 50 A˚. Similar features are observed in the silk of . Extended fibrils have an altered structure. [ABSTRACT FROM PUBLISHER]