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Histomorphometric and angiographic analysis of the humerus in pigeons
P G West1, G R Rowland, S C Budsberg
1Department of Small Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens 30602, USA.
Objective:
To identify the vascular supply and resorption/formation activity of the humerus of pigeons.
Design:
Pigeons were injected with the fluorochrome label oxytetracycline and, 5 days later, with the label calcein. 5 days after administration of the second fluorochrome, a wing from each bird was infused with a microparticle barium solution immediately after euthanasia and the chosen humerus was prepared for angiography while the opposite was prepared for histomorphometry.
Animals:
17 nine-month-old pigeons, consisting of 9 male and 8 female birds.
Procedure:
At euthanasia, 1 wing was chosen for infusion and the barium solution was injected through a catheter in the brachiocephalic artery. Both humeruses were harvested. The infused humerus was decalcified, radiographed, and sectioned for H&E staining. The opposite humerus was sectioned and measured by use of a morphometric analyzing system to determine cross-sectional area, endosteal and periosteal perimeters, and percentage of perimeter containing a single and/or double label.
Results:
All pigeons had an intramedullary arterial supply. The bones had a quiescent appearance histologically, consisting principally of lamellar bone with few osteospecialized cells, resorption surfaces, or osteons. Less than 10% of either the periosteal or endosteal surface acquired a fluorochrome label.
Conclusions:
The intramedullary vascular supply of the humerus is similar in structure to the vascular supply to mammalian bones. The humerus is, however, a quiescent bone in the sexually mature pigeon, with little remodeling activity present.
Clinical Relevance:
The intramedullary blood supply may have an important role in the healing of humeral fractures in avian species.