Absorbable surgical suture 
Surgical gut suture (Plain and Chromic) is an absorbable sterile surgical suture composed of purified connective tissue (mostly collagen) derived from either the serosal layer of beef (bovine) or the submucosal fibrous layer of sheep (ovine) intestines. The chromic gut contains a chromic salt solution to delay absorption. Surgical gut suture meets all requirements established by the United States Pharmacopeia (U.S.P.) for absorbable surgical sutures