Page 114 - Anatomy and Physiology of Farm Animals, 8th Edition

Microscopic Anatomy and Growth and Development of Bone / 99

(A) Periosteum
VetBooks.ir Compact bone

Endosteum

Bone marrow
Fibrocartilage
Cartilage

(B)

Bone

(C)

Compact
bone
Bone
marrow

Figure 5-7. Some stages in fracture healing in a long bone. (A) Early soft callus replaces a blood clot.
(B) Intermediate callus. (C) Nearly healed callus.

infant, but a similar fracture in a person have an advantage in that the portion of
past middle age may require 6 months or the bone in contact with tissue fluid may
longer to heal. survive and the osteoblasts will become
If bone healing is delayed or a major active. At the same time, osteoclasts
defect has resulted from a severe fracture remove the dead portions of the autoge-
or surgical removal of bone, grafting or nous graft, which are replaced by healthy
transplanting bone into the damaged area bone if the graft is functional and subjected
may stimulate healing. Bone for grafts may to the proper amount of stress. Osteoblasts
be obtained from the same animal that is in allografts die because the animal’s body
receiving the graft (autogenous graft) or tends to reject any foreign protein.
from another animal of the same species
(allograft). Autogenous grafts are typically
cancellous bone obtained from a site such Other Pathologic Conditions
as the proximal end of the humerus.
Allografts of cortical bone may be used if Other pathologic conditions of bones may
the bone is relatively intact or as bone chips be caused by infections, tumors, endocrine
to fill deficient areas. Autogenous grafts disturbances, or nutritional imbalances.