What is significance of biconcave shape of RBCs.

Explanation

### Step-by-Step Solution

1. **Understanding the Structure of RBCs**:
- Red Blood Cells (RBCs), also known as Erythrocytes, have a unique biconcave shape. This means they are thinner in the center and thicker at the edges, resembling a doughnut without a hole.

2. **Average Count of RBCs**:
- In a healthy adult, the average RBC count is approximately 5 to 5.5 million RBCs per cubic millimeter of blood. This high count is essential for efficient oxygen transport.

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