Short answers, pulled from the story.
Cartilage is the only tissue in the human body that contains no blood vessels, no nerves, and no lymphatic drainage. This lack of vascular supply creates a state of total sensory isolation where the tissue functions as a resilient cushion without pain until damage affects surrounding bone or soft tissue.
The body relies on three distinct classifications of cartilage defined by the ratio of collagen to proteoglycan and elastin. Elastic cartilage is found in the external ear flaps and larynx, hyaline cartilage forms the nose and trachea, and fibrous cartilage is located in the spine and knee menisci.
Chondrocytes are bound in lacunae and cannot migrate to damaged areas, making complete healing after injury extremely difficult. The lack of a blood supply means the deposition of new matrix is slow, and the tissue often relies on mechanical properties to compensate for damage until the wear and tear exceed the tissue's capacity to adapt.
Cartilaginous fish including sharks, rays, and chimaeras possess a skeleton composed entirely of cartilage without the need for ossification. This material constitutes a much greater proportion of the skeleton than in other taxa and serves as the primary structural support for their bodies.
Cartilage does not absorb X-rays under normal in vivo conditions, creating a diagnostic challenge where a dye must be injected to make the tissue appear as a void on the radiographic film. This property of invisibility allows the tissue to function as a barrier preventing the entry of lymphocytes or diffusion of immunoglobulins.