Answer:
Patches of fibrocartilage formed in the healing of a fracture are called <u>soft callus</u>, whereas the bony collar formed around the fracture is called <u>hard callus</u>.
Explanation:
In the fibrocartilage or soft bone callus phase, the necrotic bone is removed by osteoclastia and dead soft tissues are being removed by macrophages. The fibroblasts are activated and a granulation tissue is generated that supposes the appearance of new vessels and, with them, the arrival of more connective tissue cells. A tissue called fibrous callus or fibrocartilage begins to form, composed of a poorly structured amalgam of fibrous tissue, cartilage, and amorphous bone.In hard callus, bone and later cartilage are deposited in the growing historical mass. The two collars of callus, fixed to the bone at some distance from the fracture, they grow upwards and towards each other, forming an arc on focus.
The organ that living things such as fish use to extract dissolved oxygen from water are the gills. As land animals and humans don't have gills, we can't breath underwater and take in the oxygen from that source.
