| Abstract: | Measurements of haversian appositional bone formation rates were carried out on 400 haversian systems in 28-month-old standardized research colony-raised Beagles, using the midshaft of the 11th rib. The appositional bone formation rate was gradual and regular when the circumference of the outer tetracycline ring was more than 0.35 mm, but the regularity of the measured rate disappeared when the outer tetracycline ring circumference was less than 0.35 mm. Erroneous conclusions could be drawn from measurements of appositional bone formation rate in these animals if this fact were not taken into consideration, and we concluded that in pre- and postexperimental biopsy sections in the ribs of these animals, haversian systems with tetracycline ring circumferences above 0.35 mm must be measured in both situations if the differences in appositional bone formation rate are to be construed as being truly significant. |
