English: A generalized form of a spider's silk duct/ gland and spinneret. . Each differently coloured section highlights a discrete section of the gland:

Section 1: the secretory or tail section of the gland.
Section 2: the storage sac. This stores and maintains the gel-like unspun silk dope until it is required by the spider.
Section 3: The funnel rapidly reduces the large diameter of the storage sac to the small diameter of the tapering duct.

Section 4: The final length is the tapering duct, the site of most of the fiber formation. This consists of a tapering tube with several tight about turns, with a valve (5) almost at the end.