They artificially misplaced the cloaca in a chicken embryo so that it would be closer to the position of the cloaca in a snake or reptile. Accordingly, the surrounding cells started responding as ...

In mammals, the cloaca is closer to the tail bud. To further confirm this finding, the researchers grafted cloaca tissue next to the limb buds in one group of chicken embryos, and beside the tail ...

But soon afterward, for the chickens and quail, the Bmp4 gene activates in the cells at the tips of the developing penises. This gene triggers the synthesis of a particular protein called Bmp4 ...