Which of the following pairs of organs is not homologous?

Options

A. Labia majora and scrotum
B. Labia minora and foreskin
C. Clitoris and penis
D. Cowper's gland and Bartholin's gland

Answer

To determine which of the following pairs of organs is not homologous, we first need to understand the concept of homologous organs. Homologous organs are those that have a similar origin and structure but may have different functions. In contrast, analogous organs perform similar functions but have different origins and structures.

Let's analyze each option step by step:

1. **Labia Minora and Scrotum**:
- The labia minora is part of the female external genitalia, while the scrotum is part of the male reproductive system. Both structures arise from the same embryonic tissue, making them homologous.
- **Hint**: Look for structures that develop from the same embryonic origin.

2. **Labia Minora and Foreskin**:
- The labia minora covers the clitoris and is part of the vulva, while the foreskin covers the glans of the penis. Both serve a covering function, but they originate from different structures in the embryo. Therefore, they are analogous, not homologous.
- **Hint**: Compare the functions and origins of the organs to determine if they are homologous or analogous.

3. **Clitoris and Penis**:
- The clitoris and penis both arise from the same embryonic tissue and have similar structures, making them homologous organs.
- **Hint**: Identify organs that share a common embryonic origin.

4. **Cowper's Gland and Bartholin's Gland**:
- The Cowper's gland (bulbourethral gland) in males and Bartholin's gland in females are also derived from similar embryonic tissues, indicating they are homologous.
- **Hint**: Look for glands that serve similar roles in male and female reproductive systems.

After analyzing all the options, we conclude that the pair that is not homologous is:

**Answer**: Labia Minora and Foreskin (Option 2).

### Summary of Steps:
1. Define homologous organs.
2. Analyze each option for embryonic origin and function.
3. Identify the pair that does not share a common origin.