The effect of retinoic acid on chondrogenesis in the fetal hamster tibia in vivo

Chondrogenesis in the fetal hamster tibia was examined 24, 36 and 48 h after maternaladministration of retinoic acid at a known teratogenic dose (80 mg/kg) on day 10 of gestation. Twenty-four hours after treatment the tibial chondroblasts were more closely packed with less intervening fibrillar or granular matrix than in the controls. By 36 h posttreatment, an intercellular matrix containing wide clumped fibrils unassociated with matrix granules had begun to accumulate, while the chondroblasts had a relatively poorly developed Golgi apparatus and smooth, non-scalloped cell outlines. Cells frequently maintained contact through pseudopodial processes. Forty-eight hours after retinoic acid treatment, the chondroblasts appeared similar to controls of the same age. It is suggested that the paucity and abnormality of the extracellular matrix prevents the chondroblasts from assuming their normal spatial relations with each other, resulting in a small skeletal blastema.