Final answer:
Red bone marrow in adults is found in the head of the femur and flat bones, such as the ilium and scapula. Its essential function is hematopoiesis, where it produces red and white blood cells and platelets. Unlike red marrow, yellow marrow is primarily for energy storage.
Step-by-step explanation:
In adults, red bone marrow is located in certain parts of the skeleton. This marrow fills spaces within the spongy or cancellous parts of bones. Specifically, red marrow can be found in the head of the femur (thighbone), and it is also present in flat bones such as the ilium and the scapula. Its primary function is hematopoiesis—the production and differentiation of the formed elements of blood, including erythrocytes (red blood cells), leukocytes (white blood cells), and platelets. In contrast, yellow bone marrow is where adipose cells are predominant, serving primarily as a site of energy storage in the form of fat.
During early development, the embryo's blood cells originate in the yolk sac, and later, duties are taken over by organs such as the spleen, liver, and lymph nodes. Eventually, bone marrow becomes the chief site for creating blood cells through hematopoiesis. Red bone marrow is essential for the development of B cells, while T cells, referred to as thymocytes at their immature stage, leave the marrow to mature in the thymus gland.