This is an image of the intricate junction between the vertebrae of the backbone, tail and hindlimb of a veiled chameleon lizard embryo (Chamaeleo calyptratus).   In this preparation, bone is stained yellow and cartilage is stained blue.  These bones are forming by a process called endochondral ossification, in which a cartilage template is formed first and then is later partially replaced by bone.  In regions of contact between the joints, cartilage can act as a smooth surface to allow easy movement.  The chameleon has to move its limbs and tail independently; their prehensile tail acts as a fifth limb and helps the lizard with climbing trees. This image was prepared at the 2011 Woods Hole Embryology Course.