Structure and function of the silk production pathway in the Spider nephila edulis

Our observations on the major ampullate gland of the spider Nephila edulis indicate that the exceptionally tough and strong core and coat composite st ructure of the dragline thread is formed by the co-drawing of two feedstock s through a single die. The cuticle that lines the gland's duct has the str ucture of an advanced hollow fibre dialysis membrane and is thought to faci litate a rapid removal of water and change in ionic composition involved in the spinning process. A structure previously termed the 'valve' is thought to advance the broken thread and act as a pump to restart spinning after t he accidental internal rupture of a thread. Together, these observations in dicate that the spider silk production pathway is highly optimised for the production of silk threads and shows considerable biomimetic potential. (C) 1999 Elsevier Science B.V. All rights reserved.