Mature mammalian RBC is unusual because it

Options

A. Exhibits diapedesis
B. Has no nucleus
C. Is colourless
D. Can change its shape.

Answer

**Step-by-Step Text Solution:**

1. **Understanding the Question**: The question asks why mature mammalian red blood cells (RBCs) are considered unusual compared to other cells.

2. **Identifying Key Features of Mature Mammalian RBCs**:
- Mature mammalian RBCs are unique in that they lack a nucleus.
- During their development (erythropoiesis), RBCs initially have a nucleus, but they extrude it as they mature.

3. **Reason for Nucleus Extrusion**:
- The primary reason for the loss of the nucleus is to maximize space within the cell for hemoglobin.
- Hemoglobin is the protein responsible for oxygen transport, and having more hemoglobin allows RBCs to carry more oxygen.

4. **Evaluating the Options**:
- **Exhibit Diapedesis**: This refers to the movement of blood cells through capillary walls, which is not a characteristic of mature RBCs.
- **Has No Nucleus**: This is true for mature mammalian RBCs and is the correct answer.
- **Is Colorless**: RBCs are not colorless; they contain hemoglobin, which gives them their red color.
- **Can Change Its Shape**: While RBCs can deform slightly, they do not change shape significantly unless affected by a condition like sickle cell anemia.

5. **Conclusion**: The most accurate statement regarding mature mammalian RBCs is that they "have no nucleus." This characteristic is what makes them unusual compared to other cells.

**Final Answer**: Mature mammalian RBC is unusual because it has no nucleus.

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