Several mammary ducts join to form a wider `ul((A))` which is connected to `ul((B))` through which milk is sucked out.

Answer

To answer the question regarding the structures involved in milk secretion and transport in mammary glands, we can break it down step by step:

### Step-by-Step Solution:

1. **Understanding Mammary Glands**:
- Mammary glands are specialized organs in females that produce milk. They consist of several lobes, typically 15 to 20 on each side.

2. **Structure of Mammary Lobes**:
- Each mammary lobe is made up of smaller units called alveoli. These alveoli are responsible for the secretion of milk.

3. **Formation of Mammary Tubules**:
- The milk produced in the alveoli is collected into small tubes known as mammary tubules.

4. **Joining of Mammary Ducts**:
- Several mammary tubules converge to form larger structures called mammary ducts.

5. **Identification of Structure A**:
- The question states that several mammary ducts join to form a wider structure. This wider structure is known as the **mammary ampulla**.
- Therefore, A = Mammary Ampulla.

6. **Connection to Structure B**:
- The mammary ampulla is connected to another structure through which milk is expelled. This structure is called the **lactiferous duct**.
- Hence, B = Lactiferous Duct.

7. **Function of the Lactiferous Duct**:
- The lactiferous duct opens at the nipple, providing the passage through which milk is sucked out during breastfeeding.

### Final Answer:
- A = Mammary Ampulla
- B = Lactiferous Duct