In the male reproductive system of cockroaches, which of the following structures represents the external genitalia?

Options

A. Gonopore
B. Vas deferens
C. Phallomere
D. Ejaculatory duct

Answer

To solve the question regarding the external genitalia in the male reproductive system of cockroaches, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Male Reproductive System of Cockroaches**:
- The male reproductive system consists of various structures including testes, vas deferens, ejaculatory duct, and external genitalia.

2. **Identify Key Structures**:
- The **vas deferens** are two fine ducts that arise from the testes and lead to the ejaculatory duct. However, they do not represent external genitalia.
- The **ejaculatory duct** is an elongated muscular tube that opens to the outside but is not considered external genitalia itself.

3. **Locate the External Genitalia**:
- The external genitalia in male cockroaches is represented by structures known as **phallomeres** (also referred to as male gonapophysis).
- These phallomeres are chitinous structures that surround the male genital pore (gonopore).

4. **Confirm the Structure**:
- There are three phallomeres: right, left, and ventral. They are responsible for the external appearance and function of the male reproductive system.

5. **Conclude the Answer**:
- Based on the identification and confirmation of the structures, the correct answer to the question is **phallomeres** (Fallomia).

### Final Answer:
The structure that represents the external genitalia in the male reproductive system of cockroaches is **phallomeres** (Fallomia).

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