Cartilage cell. Coloured scanning electron micrograph (SEM) of a section through a chondrocyte cell (centre) in cartilage. Cartilage is a type of connective tissue formed of chondrocyte cells embedded in a matrix (blue) of collagen fibres and proteoglycans. The chondrocyte has a large nucleus (orange). The space in the matrix occupied by a chondrocyte cell is called the lacuna. Cartilage provides support for the walls of the airway, and caps the ends of long bones. Magnification: x3150 when printed 10cm wide.