RESUMO
There are no reports in literature about roles of bone morphogenetic protein 4 (BMP-4) in tooth development in mammals with complete dentition (with all dental groups). The classical model of study is the mouse, which has distinctive incisor and molar patterns. The opossum Didelphis albiventris with five upper and four lower incisors, one canine, three premolars and four molars, on each side of the jaw, seems to be a convenient model for odontogenesis study. This investigation searched for similarities and differences in BMP-4 expression pattern between the opossum and the mouse. BMP-4 cDNA was obtained by RT-PCR and the expression pattern during molar tooth development was investigated by the immunoperoxidase method. Opossum BMP-4 mature protein has 95% of sequence similarity in relation to mouse and 94% to human. The BMP-4 expression pattern during opossum tooth development was suggestive of a role in dental organ initiation and morphogenesis.