The alveoli open into.........

Answer

### Step-by-Step Solution:

1. **Identify the Context**: The question refers to the alveoli, which can pertain to different biological structures. In this case, we are discussing the alveoli of the mammary glands, not the lungs.

2. **Understand Mammary Glands**: Mammary glands are the breast tissues in females, composed of 15 to 20 lobes. Each lobe contains smaller structures that are responsible for milk production.

3. **Define Alveoli**: In the context of mammary glands, alveoli are clusters of cells that produce and secrete milk.

4. **Describe the Structure**: Each alveolus has a lumen (the inner space) where milk is secreted.

5. **Identify the Pathway**: The milk produced in the alveoli does not exit directly into the external environment. Instead, it first enters the mammary tubules.

6. **Connect to Larger Structures**: The mammary tubules from multiple alveoli converge to form mammary ducts. These ducts serve as channels for the milk to travel.

7. **Further Pathway**: The mammary ducts can join to form larger structures, such as the mammary ampulla, which is a storage area for milk before it moves into the lactiferous ducts.

8. **Final Answer**: Therefore, the alveoli open into the mammary tubules.

### Final Answer:
The alveoli open into the mammary tubules.

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