How does BMP activity affect nervous system and muscle formation in Xenopus embryos?

In Xenopus (clawed frog) embryos, the formation of the nervous system and muscles is regulated by a ventral-to-dorsal gradient of bone morphogenetic protein (BMP) activity.1

The embryo contains a signaling center known as the organizer, which secretes inhibitors of BMPs. This inhibition creates a gradient where BMP activity is lower on the dorsal side of the embryo.1

The activity of BMP in the ventral region functions to suppress the expression of transcription factors that are necessary for the development of the central nervous system and segmented muscles. By suppressing these factors, BMP activity ensures that these specific structures are restricted to the dorsal side of the embryo, where BMP levels are decreased.1