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

Background: It has been suggested that within the growth plate, the fi nal volume and shape of hypertrophic chondrocytes are important variab les in determining the rate of longitudinal bone growth. To better und erstand the organization and regulation of chondrocytic hypertrophy as related to longitudinal bone growth, the beginning and end, and the l ocation and magnitude of chondrocytic volume and shape changes during the hypertrophic process were defined in the proximal tibial growth pl ate of 35-day-old rats. Methods: In this study we used two different a pproaches, a stereological analysis of chondrocytes in unbiasedly defi ned, narrow growth plate strata, and a serial section reconstruction a nd measurement of individual cells. In both experiments chondrocytes w ere preserved using optimal chemical fixation. Proliferating chondrocy tes were identified using bromodeoxyruidine labelling, and the rate of longitudinal bone growth was determined using oxytetracycline labelli ng.