the induction of osteogenic differentation in the bone marrow stromal cell culture of rat by dexamethasone

introduction: an induction of osteogenic differentiation in rat bone marrow stromal cell cultures by dexamethasone was reported. materials and methods: the marrow stromal cells obtained from 4 to 6 weeks - old spruge-dawely male rats were grown in primary culture for 7 days and then subcultured for 20 days. the cells were cultured in either dmem medium containing 15% fetal calf serum, antibiotics and ascorbic acid; or the above medium supplemented with either 10 mm na-b glycerophosphate (na-b gp), 10-8 m dexamethasone (dex) or a combination of both. the cultures were stainded with cresyl violet, toluidine blue and alizarin red s and examined under phase-contrast microscopy. results: primary culture: the stromal cells in the primary culture formed cell colonies at day 5 and reached confluency by day 7. subculture: the bone marrow stromal cells in the subculture formed cell colonies by day 2. all subcultures reached confluency after 3 to 5 days; except those cells grown in primary cultury and subculture in the presence of dex or dex and na-bgp which failed to reach confluency at any time. the later cultures formed isolated islands of cells. at the 8th day, dense cultures of polygonal cells became evident in the centers of these islands. the cultures increased in size with time. conclusion: three-dimentional nodular structures developed in relation to the clusters at 10th to 11th days in the cultures containing both dex and na-bgp.