Final answer:
Secondary ossification centers are located in the epiphyses of long bones, where they form after birth and help in the development of the bone ends. They differ from primary ossification centers, which are established during fetal development and form the bone shaft.
Step-by-step explanation:
Long bones contain secondary ossification centers in the epiphyses, which are the expanded ends of the bone. These centers develop after birth, contributing to the formation of bone ends, while the cartilage at the epiphyseal plate facilitates growth in length. The process is part of endochondral ossification, where cartilage is replaced by bone as the individual grows towards skeletal maturity.
The primary and secondary ossification centers play critical roles in bone development. The primary ossification center appears during fetal development, forming the bone shaft. After birth, the secondary centers in the epiphyses begin to calcify, where blood vessels and osteoblasts convert hyaline cartilage into bone. This process continues until the bone reaches adult size, at which point the epiphyseal plate disappears, concluding the lengthwise growth of the bone with the fusion of the epiphysis to the diaphysis.