Final answer:
Nucleated RBCs are immature red blood cells that still contain a nucleus. They can be referred to as metarubricytes, eccentrocytes, or Heinz bodies. Howell-Jolly bodies are fragments of the nucleus that remain in red blood cells.
Step-by-step explanation:
Nucleated RBCs, also known as erythrocytes, are immature red blood cells that still contain a nucleus. These cells are called nucleated because they have a nucleus, which is typically expelled in mature erythrocytes. Nucleated RBCs are usually seen in certain diseases or conditions, such as in newborns or individuals with specific blood disorders. Other names used to refer to nucleated RBCs include metarubricytes, eccentrocytes, or Heniz bodies. Howell-Jolly bodies, on the other hand, are fragments of the nucleus that remain in the cell after the normal expulsion of the nucleus during RBC maturation. They are often seen in individuals with certain medical conditions, such as splenectomy or certain types of anemia.