BACKGROUNDThe palate is differently regulated and developed along the anterior-posterior axis. The Bmp signal pathway plays a crucial role in palatogenesis. Conditioned-inactivation of Bmp type I receptor Alk2 or Alk3 in the neural crest or craniofacial region leads to palatal cleft in mice. However, how different Bmp members are involved in palatogenesis remains to be elucidated. In the present study, mRNA expression patterns of Bmp2, Bmp3 and Bmp4 in the developing anterior and posterior palates were examined and compared, focusing on the fusion stage.

METHODSTo detect the expression of Bmp mRNA, antisense riboprobes were synthesized by in vitro transcription. Radioactive in situ hybridization was performed on sagital and coronal sections of mice head from E13 to E18.

RESULTSThe expression of these Bmps were developmentally regulated in the anterior and posterior palates prior to, during and after palatal fusion. During palatal fusion, Bmp4 expression shifted from the anterior to the posterior palate, Bmp2 was highly expressed in both the anterior and posterior palates in this process, whereas Bmp3 was only localized in the posterior palate. They showed generally non-overlapping pattern in their expression domains. Thereafter, their expression was detected in both the anterior and posterior palates regulating osteogenesis and myogenesis respectively.

CONCLUSIONSBmp signalling is involved in palatogenesis in multiple stages and has multiple roles in regulating anterior and posterior palatal development. Disturbances of Bmp signalling during palatogenesis might be a possible mechanism of cleft palate.