Spinning apparatus for the dragline silk in the funnel‐web spider Agelena Limbata (Araneae: Agelenidae)

Abstract

Among the four kinds of silk glands in the funnel‐web spider Agelena limbata, the ampullate gland for dragline silk production is the most predominate one in both sexes, and is composed of three functional parts ‐excretory duct, storage ampulla and convoluted tail regions. Two pairs of major ampullate glands send secretory ductules to the anterior spinnerets, and another two pairs of minor ampullate glands supply the middle spinnerets. There are no apparent differences between the major and minor ampullate glands not only the external spigots but also their internal silk glands. However, the microstructure is very unique in this spider, because each gland has spherical shaped storage sac with twig‐like branched tails. Nevertheless, the wall of the secretory region is similarly composed of a single layer of epithelial cells. The mature secretory silks in glandular epithelium are closely packed and accumulated as electron‐opaque vesicles. Most of the secretory products which originated from the rough endoplasmic reticula (rER) are grown up by fusion with the surrounding small vesicles however, the Golgi complex does not seem to play an important role in this process of secretion.

Key words:

• fine structure
• silk apparatus
• funnel‐web spider
• Agelena limbata

Notes

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