Bone metastasis may be the first sign that you have cancer, or bone metastasis may occur years after cancer treatment. Bone metastasis can cause pain and broken bones. With rare exceptions, cancer that has spread to the bones can't be cured. Treatments can help reduce pain and other symptoms of bone metastases.
Medical Definition of Chondrichthyes. : a class comprising cartilaginous fishes with well-developed jaws and including the sharks, skates, rays, chimeras, and extinct related formsâcompare cyclostomata.
The Chondrichthyes are the cartilaginous fishes including the sharks, rays, skates and chimaeras. The Osteichthyes are the bony fish. Both of these groups became established d â¦ uring the Devonian Period about 400 million years ago.The Chondrichthyes differ from the Osteichthyes in many respects, including their skeletons, scales, teeth, buoyancy, swimming, gills and reproduction. Scales:   Cartilaginous fish have large scales called placoid scales. These have a bone like base embedded in the skin and a backward projecting enamel covered dentine spine. The whole thing has a central pulp cavity (rather like the structure of teeth). The epidermis and dermis form placoid scales.