Ampullate gland

Casern, M. L., Tran, L. P. P., and Moore, A. M. F. (2002). Ultrastructure of the major ampullate gland of the black widow spider, Latrodectus hesperus. Tissue Cell 34, 427-436. 

Figure 6 Schematic representation of major ampullate gland (a). The various parts of the gland and their function, as well as the structure of silk under each part, are shown (Lewis, 2006). Also shown is a model of chain folding, micelle formation, globule formation and curing, and shear processing of silk proteins. This model is motivated by experiments in vitro (Jin and Kaplan, 2003) (b).

Figure 5 Mechanism of fiber formation in the spicier major ampullate gland. Schematic process of silk secretion and fiber formation, from left to right. Silk protein is represented in green, and the gland cells/wall in orange. Flow is from left to right. Adapted from Michael Ellison, Clemson University.

Cunniff, P.M., Fossey, S.A.. Auerbach, M.A. and Song, J.W. (1994) Mechanical properties of major ampullate gland silk fibers extracted from Nephila clavipes spiders. In Silk Polymers Materials Science and Biotechnology, pp. 234-251, D. Kaplan, W.W. Adams, B. Farmer and C. Viney (Eds.). American Chemical Society. Washington, DC. 

Recent investigations of the gel-like protein content gathered and stored in the sac-like glands of the major ampullate glands revealed that the majority... 

The C-termini of the spidroins derived from ampullate glands are highly... 

Sponner, A., Unger, E., Grosse, F. and Weisshart, K., Conserved C-termini of spidroins are secreted by the major ampullate glands and retained in the silk thread. Biomacromolecules, 2004, 5(3) 840-5. 

In addition to silk moths/worms, silks are produced by many other species of insects and spiders (Kaplan et al., 1992, 1993, 1998). Unlike silk moth-derived silk, spider silks are not widely used in the textile industry because of their limited availability. Spiders naturally produce less silk than a silkworm cocoon ( 137 m of fiber can be obtained from the ampullate gland of a spider while one silkworm cocoon yields 600-900 m of fiber) (Lewis, 1996) and, spiders being solitary and predatory in nature, cannot be raised in large numbers. However, it was documented that spider silks are just as suitable for textile production as their insect counterparts (Kaplan et al., 1993). Consequentially, for biomaterial development, silk moths/worms and spiders are the main silk sources. 

Silk fibers formed by the secretion of the major ampullate glands of the spider Nephila clavipes also involve the linear supramolecular aggregation of a globular protein (fibroin). The formation of rodlike aggregates is consistent with the observation of a precursor liquid crystalline phase before fiber solidification [135,136]. Details of this supramolecular polymerization are still unclear. 

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