Vertebral growth. A, Body endplates (superior and inferior; labeled as A). B, Neurocentral cartilage (bipolar) fusion at age 7 or 8 years (labeled as B). C, Posterior elements cartilage (labeled as C). L, Ring apophysis (begins at age 7 to 9 years, closed at age 14 to 24 years); P, periosteum.