Platypus x-rays show shadows of its “reptilian” ancestry

Platypuses belong to an ancient group of mammals, the monotremes. Today, these are the only living mammalian species to lay eggs, and the group also includes echidnas. But, as the x-rays of┬áDr Larry Vogelnest show, the platypus retains several skeletal features which link it to its distant ancestors (often called reptiles, but more technically referred…

Cartilage and encroaching bone in the developing mouse skeleton

This shot of the dorsal neck of a developing mouse embryo visually shows the process of skeletal growth found in all bony vertebrates. The widespread blue stain (Alcian blue) reveals the extensive cartilaginous blueprint for the growing skeleton, which extends by the division of chondrocytes (cartilage-producing cells) guided by signalling molecules across the embryo. The…