Find the odd one out with respect to the mode of chemical secretion.

Options

A. Pineal gland
B. Pituitary gland
C. Thyroid gland
D. Mammary gland

Answer

To solve the question of finding the odd one out with respect to the mode of chemical secretion, we will analyze the given options: pineal gland, pituitary gland, thyroid gland, and mammary gland.

### Step 1: Identify the type of glands
- **Pineal Gland**: This is an endocrine gland that secretes hormones directly into the bloodstream. It primarily produces melatonin, which regulates sleep-wake cycles.

- **Pituitary Gland**: Known as the "master gland," it is also an endocrine gland that releases various hormones into the bloodstream, influencing other glands and bodily functions.

- **Thyroid Gland**: This is another endocrine gland that secretes hormones like thyroxine, which regulates metabolism. It also releases calcitonin, which helps control calcium levels in the blood.

- **Mammary Gland**: This gland is primarily responsible for producing milk in females. It is classified as an exocrine gland because it secretes its products through ducts (specifically, the milk is secreted through the nipple).

### Step 2: Classify the glands based on their secretion mode
- **Endocrine Glands**: Pineal gland, pituitary gland, and thyroid gland are all endocrine glands. They secrete hormones directly into the bloodstream without the use of ducts.

- **Exocrine Gland**: The mammary gland is an exocrine gland, which means it has ducts that carry its secretions (milk) to the surface (nipple).

### Step 3: Determine the odd one out
Since the mammary gland is an exocrine gland and the other three (pineal, pituitary, and thyroid glands) are endocrine glands, the mammary gland is the odd one out in this context.

### Conclusion
The correct answer is the **mammary gland** because it is the only exocrine gland among the options provided, while the others are all endocrine glands.

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