An absent kidney is found in –
**Core Concept**
The question is testing the student's knowledge of the development of the human embryo, specifically the embryological origin of the kidneys. The kidneys develop from the intermediate mesoderm, which differentiates into the metanephric mesenchyme and the ureteric bud. The metanephric mesenchyme gives rise to the nephrons, while the ureteric bud forms the collecting ducts, calyces, and the ureter.
**Why the Correct Answer is Right**
The correct answer is related to the embryological origin of the kidneys. In humans, the kidneys develop from the intermediate mesoderm, which is located between the paraxial mesoderm (which forms the somites) and the lateral plate mesoderm (which forms the heart and blood vessels). The metanephric mesenchyme, which is a subset of the intermediate mesoderm, gives rise to the nephrons, while the ureteric bud forms the collecting ducts, calyces, and the ureter. An absent kidney can occur if there is a developmental failure of the metanephric mesenchyme or the ureteric bud.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not directly related to the embryological origin of the kidneys.
**Option B:** This option is incorrect because it is not a known embryological structure related to kidney development.
**Option C:** This option is incorrect because it is a different embryological origin altogether, related to the development of the digestive system.
**Clinical Pearl / High-Yield Fact**
It's worth noting that an absent kidney can occur due to various reasons, including developmental anomalies, congenital anomalies, and acquired conditions such as renal agenesis or ectopic kidney. This knowledge is crucial in diagnosing and managing patients with renal abnormalities.
**Correct Answer: D. Suprarenal gland**