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Unformatted text preview: Bone Development The skeleton arises from fibrous membranes and hyaline cartilage during the first month of embryonic development. These tissues are replaced with bone by two different bone-building, or ossification, processes. The first process, called intramembranous ossification, occurs when fibrous membranes are replaced by bone tissue. The process, occurring only in certain flat bones, such as the flat bones of the skull, sternum, and clavicle, is summarized in two basic steps: 1. Spongy bone tissue begins to develop at sites within the membranes called centers of ossification. 2. Red bone marrow forms within the spongy bone tissue, followed by the formation of compact bone on the outside. The second ossification process, called endochondral ossification, occurs when hyaline cartilage is replaced by bone tissue. The process, occurring in most bones of the body, follows these steps: replaced by bone tissue....
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- Spring '10