Cello inexpensive wood that has been blackened or "ebonized" to look like ebony, which is much harder and more expensive. Ebonised parts such as tuning pegs may crack or split, and the black surface of the fingerboard will eventually wear down to reveal the lighter wood underneath. Historically, cello strings had cores made out of catgut, which, despite its name is made from sheep or goat intestines which are dried out. Most modern strings used in the 2010s are wound with metallic materials like aluminum, titanium and chromium. Cellists may mix different types of strings on their instruments. The pitches of
Catgut suture anemia, and malnutrition. It also absorbed faster when used in the mouth and the vagina, due to the presence of microorganisms. Catgut has largely been replaced by synthetic absorbable polymers such as Vicryl and polydioxanone. It is not used at all for human surgery in some countries. In Europe and Japan, gut sutures have been banned due to concerns that they could transmit bovine spongiform encephalopathy (mad-cow disease), although the herds from which gut is harvested are certified BSE-free. Catgut suture is made by twisting together strands of purified collagen taken from the serosal or submucosal layer of the small