Skeleton intervertebral discs. It is not as hard and rigid as bone but is stiffer and less flexible than muscle. Cartilage is composed of specialized cells called chondrocytes that produce a large amount of extracellular matrix composed of Type II collagen (except Fibrocartilage which also contains type I collagen) fibers, abundant ground substance rich in proteoglycan, and elastin fibers. Cartilage is classified in three types, elastic cartilage, hyaline cartilage and fibrocartilage, which differ in the relative amounts of these three main components. Unlike other connective tissues, cartilage does not contain blood vessels. The chondrocytes are supplied by diffusion, helped by the
Cartilage conduction with robots. Currently, loudspeaker systems are used to convey sounds produced by robots. However, such loudspeakers generate loud noises in a room filled with many robots that simultaneously emit speech sounds. Therefore, a man-to-man communication system is needed to overcome this problem. Cartilage conduction can realize better communication than loudspeaker systems. It was initially thought that cartilage conduction was a type of bone conduction. However, several studies demonstrated that the mechanisms of cartilage conduction differ from that of bone conduction. Bone conduction is attributed to bone vibration at the skull, which is transmitted to the inner ear. In contrast, cartilage