Why is it that frog blood smear shaped as oval?

Frog blood smears appear oval primarily due to the shape of the red blood cells, which are oval or ellipsoid in many amphibian species. Unlike mammalian red blood cells that are biconcave discs, frog erythrocytes retain their nucleus and have a more elongated shape. This design helps optimize gas exchange and can be beneficial for their aquatic and terrestrial habitats. The oval shape is a characteristic feature of their physiology and evolutionary adaptations.