Final answer:
Red blood cells are produced in the red marrow of bones through a process called hematopoiesis. They are specialized cells that carry hemoglobin and lack a nucleus and most organelles.
Step-by-step explanation:
Red blood cells are produced in the red marrow of long bones, rib bones, the skull, and vertebrae. The red marrow is where hematopoiesis, the production of blood cells, takes place. Red blood cells, or erythrocytes, are highly specialized cells that are filled with hemoglobin and lack a nucleus and most organelles to maximize space for hemoglobin.