What does "segmental" mean?

Segmental: (Anat. & Zoöl.) (a) Of or pertaining to the segments of animals; as, a segmental duct; segmental papillæ. (b) Of or pertaining to the segmental organs. Segmental duct (Anat.), the primitive duct of the embryonic excretory organs which gives rise to the Wolffian duct and ureter; the pronephric duct. -- Segmental organs. (a) (Anat.) The embryonic excretory organs of vertebrates, consisting primarily of the segmental tubes and segmental ducts. (b) (Zoöl.) The tubular excretory organs, a pair of which often occur in each of several segments in annelids. They serve as renal organs, and often, also, as oviducts and sperm ducts. See Illust. under Sipunculacea. -- Segmental tubes (Anat.), the tubes which primarily open into the segmental duct, some of which become the urinary tubules of the adult.