## **Core Concept**
The Weigert-Meyers rule, also known as the Weigert-Meyer rule, explains the relationship between the upper and lower pole ureters in a duplicated collecting system and their termination points in the urinary bladder. This rule is crucial in understanding the anatomy of duplicated ureters.

## **Why the Correct Answer is Right**
The Weigert-Meyer rule states that in a complete duplication of the ureter, the **upper pole ureter** is associated with an **ectopic ureter** (often obstructed and sometimes ectopically located outside the bladder) and a **ureterocele**, while the **lower pole ureter** has a **greater tendency to reflux** due to its more lateral and caudal insertion into the bladder. The lower pole ureter usually opens in a more **orthotopic** (normal) position but with a **shorter intramural tunnel**, predisposing it to vesicoureteral reflux. Therefore, according to this rule, the lower pole ureter opens **more distally** and **laterally** in the bladder.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option does not accurately describe the typical insertion site according to the Weigert-Meyer rule.
- **Option B:** Similarly, this option does not align with the anatomical description provided by the rule.
- **Option C:** This option suggests a more proximal and medial insertion, which is not consistent with the Weigert-Meyer rule for the lower pole ureter.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that in a duplicated collecting system, the **lower pole ureter is more likely to have vesicoureteral reflux** due to its abnormal insertion. This is critical for pediatric patients and those with urinary tract infections, as it guides diagnostic and therapeutic decisions.

## **Correct Answer:** D. distally and laterally.