is the process of bone
formation, in which connective tissues, such as cartilage
are turned to bone or bone-like tissue. The ossified tissue is invaginated with blood vessels. These blood vessels bring minerals
and deposit it in the ossifying tissue. Bone formation is a dynamic process, with cells called osteoblasts
depositing minerals, and osteoclasts
removing bone. This process, termed bone remodeling
continues throughout life.
Types of ossification
Several hypotheses have been proposed for how bone evolved as a structural element in vertebrates
. One popular idea is that bone developed from tissues that evolved to store minerals
. In this model, minerals such as calcium were stored in cartilage
, and that bone was an exaptation
from this ossified cartilage
. However, other possibilities include bony tissue evolving as an osmotic barrier, or as a protective structure.