Topics:
Animal Physiology, Animal Refresher
Species with Nucleated Erythrocytes and Thrombocytes
Erythrocytes (RBC) & thrombocytes (platelets) are nucleated in:
- Fowl — Correct Answer
- Camel
- Dog
- Cattle
Explanation:
Correct Answer: Fowl
Birds (Fowl) are unique among vertebrates in having nucleated erythrocytes (RBCs) and nucleated thrombocytes (platelets). Mammals, in contrast, have anucleate (no nucleus) mature erythrocytes and anucleate platelets (thrombocytes are cell fragments).
Why Avian RBCs Are Nucleated
- Birds never lost the nucleus from their red blood cells during evolution, unlike mammals.
- Avian RBCs are elliptical/oval and nucleated, making them larger but less deformable than mammalian biconcave anucleate RBCs.
- Despite nuclei, avian RBCs are still efficient at oxygen transport due to their large surface area.
Why Mammalian RBCs Are Anucleate
- Mammalian erythrocytes eject their nucleus during maturation to maximize space for hemoglobin and allow biconcave disc shape for flexibility in capillaries.
- Camel RBCs are ellipsoidal (oval biconcave) but still anucleate — they are unique among mammals for their oval shape (adaptation for water conservation).
Summary Table
- Nucleated RBCs & platelets: Birds, Reptiles, Amphibians, Fish
- Anucleate RBCs & platelets: Mammals (cattle, horse, dog, goat, etc.)
📚 About this Topic — Animal Physiology
This multiple choice question is from Animal Physiology, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Physiology to strengthen your preparation.
