Danielle Rux, Graduate Student (Wellik laboratory), Department of Cell and Developmental Biology, University of Michigan Medical School

This is a section from the forelimb of an adult mouse showing its growth plate. In fetal and adolescent stages, the growth plate of long bones is the developmental center for new bone formation and it is located at the ends of each long bone.  The zone of red here represents the cartilage from which bone is developed.  During growth, the cartilage cells die and osteoblasts (bone-forming cells) ossify the remains.  In adult stages, like the one shown here, the growth plate ceases to form new bone and simply maintains the line of cartilage.