Renal Development: Stages and Derivatives
The renal system develops from the intermediate mesoderm in three successive stages, moving from cranial to caudal.
| Structure | Timeline/Fate |
|---|---|
| Pronephros | Week 4: non-functional; degenerates. |
| Mesonephros | First trimester; contributes to the Wolffian duct; later forms the male genital system. |
| Metanephros | Functional kidney (permanent). Starts in week 5; urine production starts in week 10. |
High-Yield Developmental Components:
- Ureteric Bud: Derived from the mesonephric duct. Gives rise to the ureter, renal pelvis, calyces, and collecting ducts.
- Metanephric Mesenchyme: Gives rise to the nephron (glomerulus to distal convoluted tubule).
- Clinical Correlates:
- Potter Sequence: Bilateral renal agenesis leads to oligohydramnios, causing pulmonary hypoplasia, limb deformities, and characteristic facial features (“Potter facies”).
- Horseshoe Kidney: Kidneys fuse at the lower poles and get “trapped” under the inferior mesenteric artery during ascent.