STEREOLOGICAL AND SERIAL SECTION ANALYSIS OF CHONDROCYTIC ENLARGEMENT IN THE PROXIMAL TIBIAL GROWTH-PLATE OF THE RAT

Background: It has been suggested that within the growth plate, the final volume and shape of hypertrophic chondrocytes are important variables in determining the rate of longitudinal bone growth. To better understand the organization and regulation of chondrocytic hypertrophy as related to longitudinal bone growth, the beginning and end, and the location and magnitude of chondrocytic volume and shape changes during the hypertrophic process were defined in the proximal tibial growth plate of 35-day-old rats. Methods: In this study we used two different approaches, a stereological analysis of chondrocytes in unbiasedly defined, narrow growth plate strata, and a serial section reconstruction and measurement of individual cells. In both experiments chondrocytes were preserved using optimal chemical fixation. Proliferating chondrocytes were identified using bromodeoxyruidine labelling, and the rate of longitudinal bone growth was determined using oxytetracycline labelling.