effects of retinoic acid on tibia osteogenesis in chick embryo

introduction: the objective of this study was to evaluated effect of retinoic acid (ra) on the tibia osteogenesis in the chick embryos. materials and methods: for this purpose 0.75mg ra dissolved in 2ml dimthylsulfoxide (dmso) was droped on the limb bud of chick embryos at sixth day of incubation. the osteogenesis of tibia in ra-treated embryos were compared with normal control and dmso-treated groups (in the same stage) in days 9, 10, 11, 12 and 13 by microscopic and statical analysis. the tibia in all groups were cut, fixed, decalcified, processed in paraffin, serially sectioned and stain with hematoxyline and eosin. the volumes of bone formation, cartilage, connective 8 vascular tissue and the volume of the whole of tibia were calculated. results: retinoic acid has resulted in an increase in mortality rat and a decreased in the body weigh of the chick embryo. in addition to that, ra has resulted in the reduction of osteogenesis, connective and vascular tissue morphogenesis and resorption of the cartilage and consequently the volume of tibia has reduced. conclusion: retinoic acid can retartd tibia osteogenesis in chick embryos.