[Post-natal development of tooth structures in Didelphis albiventris].

The post-natal development of tooth germs has been studied in the opossum or South American marsupial (Didelphis albiventris) between the 2nd and 10th week. Dentinogenesis starts around the 3rd week. The enamel which begins to appear at this stage is deposited until the 8th-10th week. At 10 weeks, the enamel enters the maturation phase. It is unlikely that enamel tubules in these marsupials have a cellular origin. No specific histochemical reaction predicts their appearance which is observed in the mature tooth. This fact suggests that their origin is related either to enamel maturation or to the beginning of tooth function. The mineralizing dentine front presents on the one hand calcospherites where peritubular dentine is formed before intertubular dentine, and on the other hand a radiating mineralizing structure. These two aspects are exceptional in Vertebrates.