[Reorganization of growth-plate-like tissue by isolated chondrocytes in culture].

Growth-plate cartilage is organized into four cellular zones containing resting, proliferating, maturing, and hypertrophic cells. Rabbit chondrocytes were isolated from growth-plate costal cartilage of 4-week-old New Zealand rabbits, the cells (15 x 10(4)) were suspended in 1 ml of Iscove's modified Dulbecco's medium (IMDM) with 10% fetal bovine serum, 50 micrograms ascorbic acid, and 60 micrograms kanamycin (medium A), then transferred to a 15 ml of plastic centrifuge tube, and centrifuged at 1500 rpm for 5 min. The cell pellet was incubated at 37 degrees C under 5% CO2 in air. The cultures reorganized into growth plate-like tissue which could be seen 7-14 days after cell seeding. This growth-plate, histologically, was organized longitudinally into cellular columns and horizontally into four cellular zones containing resting, proliferating, maturing and hypertrophic cells. The hypertrophic cells in the upper were large in size and round or oval in shape, the proliferating and the mature chondrocytes in the lower were small in size and spherical or elongated in shape. These chondrocytes were surrounded by an extensive matrix. Biochemically, DNA content of cultures began to rise on the 2nd day after cell seeding and reached a plateau after 10 days later. The uronic acid content increased from day 4 and reached the maximum on day 15. In contrast in the early culture, alkaline phosphatase activity was extremely low, it began to rise on day 9 and was the highest on day 20. The sequential increase of DNA, uronic acid and alkaline phosphatase contents was analogous to the in vivo changes of growth-plate chondrocytes.