A prenatal ultrasound at 20 weeks reveals that a fetus is developing normally; however, a genetic study performed due to a family history of renal anomalies shows a mutation affecting the signaling pathway between two renal embryologic structures. Based on embryologic development, which interaction is most crucial for the formation of the permanent kidney that begins to appear around the 5th week of gestation? Key Details: • Abnormal signaling is suspected between two interacting tissues during kidney development • The permanent kidney is known to develop after the regression of the transient renal structures • The study emphasizes the importance of inductive interactions during organogenesis