DENSE BONE
Figure 7­16
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Holdings,
Bone provides the main structural and protective support for the body. Skeletal muscles and ligaments insert into
bone, and the tissue protects the brain and organs of the thoracic cavity. It is a storehouse for calcium and phos-
LLC.
phorus and functions as a blood-forming organ.
Not
Histologically, there are two types of bone tissue: dense (compact) bone and spongy (cancellous) bone. Compact
to
bone is characterized by mature bone cells, or osteocytes, housed in lacunae and arranged in patterns around blood
be
vessels. There is a great amount of matrix associated with the osteocytes, separating one osteocyte from others.
redistributed
The organization of cancellous bone has less matrix and more cellular material than compact bone and will be de-
scribed more completely later in this chapter.
or
The image depicts an area of dense bone located at the periphery of one of the long bones of the body. The clear,
modified
open spaces (arrowheads) within the tissue are channels that house blood vessels and nerves. Unlike cartilage,
which is an avascular tissue, bone has a rich blood supply. At the lower left portion of the field is the marrow cavity,
in
which is a blood forming organ. Several adipocytes occupy parts of the marrow cavity.
any
way
At the right of the field is a thin band of connective tissue that is adherent to bone; this is the periosteum (arrow).
It consists of an outer layer of dense connective tissue and an inner zone of osteoprogenitor cells, primitive cells
without
that can differentiate into osteoblasts capable of secreting the components of the matrix. These two layers have
separated from each other in the preparation of the specimen. In addition, the area of bone adjacent to the marrow
permission.
cavity is lined by endosteum, a thin layer of connective tissue that also contains osteoprogenitor cells.
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