Developmental arrest of mouse tooth germs in vitro by 6-diazo-5-oxonorleucine (DON)

Molars and incisors were excised from the mandibles of 15-day-old mouse embryos and explanted to agar-solidified Eagle's basal medium with 10% fetal calf serum and to medium containing 6-diazo-5-oxonorleucine (DON), a glutamine analog which inhibits glycoprotein and glycosaminoglycan synthesis. The concentration of DON ranged from 5-100 microgram/ml; the lowest dose at which consistent results were obtained was 75 microgram/ml. At the end of a 4-day culture period, controls displayed characteristic incisiform or molariform morphologies and possessed odontoblasts and preameloblasts. The growth and development of DON-treated germs, however, was arrested and such germs remained morphologically and histologically similar to the developmental state attained at the time of explantation. DON-treated germs also contained less abundant Alcian blue staining material than controls. Development arrest by DON was prevented by addition of glutamine but not by glucosamine or the purine analog amino imidazol carboximine. Suppressed germs resumed normal development when removed from medium containing 75 microgram/ml of DON to control medium. These results suggest that glycoprotein or glycosaminoglycans play a role in epithelial-mesenchymal inductive interactions.