Why is yolk sac absent in human female?

Explanation

### Step-by-Step Solution:

1. **Understanding the Yolk Sac**: The yolk sac is an extra-embryonic structure that provides nutrition to the developing embryo in many species. It is particularly important in species where the embryo develops outside the mother's body.

2. **Presence in Other Species**: In many animals, the yolk sac is crucial for the nourishment of the embryo during the early stages of development, especially in species with larger amounts of yolk in their eggs.

3. **Human Egg Characteristics**: In humans, the egg is classified as "micro-lacetal," meaning it has a very small amount of yolk. This is due to the fact that the human egg contains mainly nucleus and cytoplasm, which are essential for cell division and development.

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