Final answer:
By 25 years of age, hematopoiesis no longer takes place in the medullary cavity of long bones, occurring instead in the red bone marrow of certain bones like the vertebrae, sternum, and pelvis.
Step-by-step explanation:
Hematopoiesis is the process of blood cell and platelet production that occurs in the body continuously, due to the brief lifespan of these formed elements. By 25 years of age, hematopoiesis no longer takes place in the medullary cavities of the long bones. Instead, in adults, this process is primarily restricted to the cranial and pelvic bones, vertebrae, sternum, and the proximal ends of the femur and humerus. The liver and spleen have the potential for extramedullary hematopoiesis, which is blood cell production outside of the medullary cavity, as a compensatory mechanism when bone marrow is damaged or destroyed by diseases such as bone cancer.