Final answer:
Once an individual reaches maturity, the growth plates (epiphyseal plates) in the bones close as the cartilage is replaced by bone, ending longitudinal growth. This leads to the formation of the epiphyseal line, a remnant of the former growth plate, and signifies that the bones have reached their full adult length.
Step-by-step explanation:
What Happens to the Growth Plate Once Fully Grown
During childhood and adolescence, bones lengthen through a process involving the epiphyseal plate, commonly referred to as the growth plate. When an individual reaches full maturity—around 18 years for females and 21 years for males—the chondrocytes (cartilage cells) within the epiphyseal plate stop dividing and the entire cartilage is replaced by bone. This transition from cartilage to bone marks the end of longitudinal bone growth, resulting in the formation of the epiphyseal line, a remnant of the former growth plate. This process, known as epiphyseal plate closure, signifies that the bones have achieved their maximum length and the epiphysis has fused with the diaphysis to form a mature bone structure.