The retroperitoneal kidney is

Options

A. Kidney of fish
B. Kidney covered by peritoneum on ventral side
C. Kidney covered by peritoneum on dorsal side
D. Kidney uncovered by peritoneum on either side

Answer

**Step-by-Step Solution:**

1. **Understanding the Term "Retroperitoneal":**
The term "retroperitoneal" refers to the anatomical space located behind the peritoneum, which is the membrane lining the abdominal cavity. Organs that are classified as retroperitoneal are not suspended by mesentery and are located between the peritoneum and the abdominal wall.

2. **Identifying the Kidney's Position:**
In the context of the kidneys, they are positioned at the posterior end of the abdominal cavity. This means they are located towards the back of the body, behind the peritoneal lining.

3. **Analyzing the Coverage of the Kidney:**
The kidneys can be covered by peritoneum in different ways. For a kidney to be classified as retroperitoneal, it should have peritoneum covering it only on the anterior (ventral) side, while the posterior (dorsal) side remains uncovered.

4. **Conclusion:**
Based on the definition and characteristics of retroperitoneal organs, the correct description of a retroperitoneal kidney is that it is covered by peritoneum on the ventral side only. Therefore, the answer to the question is that the retroperitoneal kidney is the one that is covered by peritoneum on the ventral side.

**Final Answer:**
The retroperitoneal kidney is covered by peritoneum on the ventral side.

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