os

(plural ossa))

bone (the hard connective tissue consisting of cells (osteoblasts, osteocytes) in a mixture of collagen fibres and hardened by calcium and phosphate salts (calcium hydroxyapatite), serving to support the body. The cells are lost eventually leaving cavities and the bone is termed cellular, typical of Dipnoi, Crossopterygii, Chondrostei, primitive Teleostei, e.g. Cyprinidae, Siluridae, Salmonidae, Anguillidae, and some advanced Teleostei, e.g. Perca, Gadus. Another form of bone is termed osteoid and lacks the ramifications seen in cellular bone. After the osteocytes disintegrate, the spaces they leave are filled with matrix and the bone is known as acellular, e.g. in Cyclopterus, Mola. Bone is strong and rigid in contrast to cartilage). Older works on fish anatomy may have bones listed in Latin, hence the following entries. Plural forms are given for those unfamiliar with Latin. Note that some bone and skeletal names in English are the same in English and Latin, e.g. branchiocranium, and the majority of English names are derived from the Latin name, merely having different word endings