Cartilage as the cricoid cartilage and carina. Cartilage is composed of specialized cells called chondrocytes that produce a large amount of collagenous extracellular matrix, abundant ground substance that is rich in proteoglycan and elastin fibers. Cartilage is classified in three types, "elastic cartilage", "hyaline cartilage" and "fibrocartilage", which differ in relative amounts of collagen and proteoglycan. Cartilage does not contain blood vessels (it is avascular) or nerves (it is aneural). Nutrition is supplied to the chondrocytes by diffusion. The compression of the articular cartilage or flexion of the elastic cartilage generates fluid flow, which assists diffusion of nutrients to the chondrocytes.
Cartilage invertebrate cartilage that shows more resemblance to the vertebrate hyaline cartilage. The growth is though to take place throughout the movement of cells from the periphery to the center. The chondrocytes present different morphologies related to their position in the tissue. The embryos of "Sepia officinalis" express ColAa, ColAb and hyaluronan in the cranial cartilages and other regions of chondrogenesis. This implies that the cartilage is fibrillar-collagen-based. The "Sepia officinalis" embryo expresses hh, whose presence causes ColAa and ColAb expression and is also able to maintain proliferating cells undiferentiated. It has been observed that this species presents the expression SoxD