Which type of blood cells lack a nucleus?

Erythrocytes, or red blood cells, are the type of blood cells that lack a nucleus. This unique characteristic allows them to maximize their hemoglobin content, which is essential for carrying oxygen throughout the body effectively. The absence of a nucleus gives erythrocytes more space to transport oxygen and increases their flexibility as they navigate through narrow blood vessels.

While leukocytes, or white blood cells, are crucial for the immune system and do contain a nucleus, platelets (which are cell fragments) and thrombocytes (which are another term for platelets, particularly in non-mammalian species) are also nucleated or fragmentary in nature. In mammals, it is erythrocytes that uniquely possess a biconcave disc shape and lack a nucleus, distinguishing them clearly from other blood cells.