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.
C. Pharyngeal pouches. D. Endostyle-elongated groove in the pharynx floor of protochordates that may develop as the thyroid gland in chordates. These four characteristics may be found in some of the ancestors of chordates and are commonly placed in an informal grouping called Protochordates.These serve as living representations of the missing fossils in vertebrate evolution.n contrast to protochordates (hemichordates, urochordates, and cephalochordates), vertebrates are actively-feeding, predatory organisms that move by lateral undulation of an elongate body. Hemichordates and most urochordates are also filter-feeders, moving water through their gill slits, but are sessile as adults.