part of cortical layer of collagen and cuticulin-based cuticle extracellular matrix annular furrow extracellular matrix The extracellular matrix part that is a regularly spaced indentation in the outer cortical layer of the cuticle. The pattern of annular furrows corresponds to sites of invaginations in hypodermal cell membranes that, in turn, correspond to submembranous regions where actin microfilament bundles assemble early in lethargus, the first phase of the molting cycle in which activity and feeding decline. cellular_component GO:0060108 cellular anatomical structure