Which of the following statements about the ureters is correct in human anatomy?

Introduction / Context:
The ureters are muscular tubes that carry urine from the kidneys to the urinary bladder. Although they are relatively small structures, their function is vital for normal excretion of urine. Exam questions often test detailed knowledge of their structure and function, including innervation, epithelial lining, and the way urine is propelled. This question asks you to identify the correct statement among several common misconceptions.

Given Data / Assumptions:

• The focus is on human ureters.
• Options discuss innervation, sphincters, epithelial type, and peristalsis.
• We assume familiarity with smooth muscle and epithelial tissue types.

Concept / Approach:
The ureters are lined by transitional epithelium (urothelium), not stratified squamous epithelium like the skin. This special epithelium allows the ureter walls to stretch as urine passes. The muscular wall of the ureter contains smooth muscle that contracts in rhythmic waves known as peristalsis, pushing urine from the renal pelvis down to the bladder, even against gravity. There are no true anatomical sphincters at the ureter bladder junction; instead, the ureters enter the bladder obliquely, and the bladder wall compresses the ureter openings when it fills, helping to prevent reflux. Innervation involves both sympathetic and parasympathetic fibres, not parasympathetic only.

Step-by-Step Solution:
Step 1: Recall that ureters are muscular tubes that actively transport urine by peristaltic waves, not just by gravity. Step 2: Recognise that transitional epithelium lines the urinary tract from renal pelvis to bladder, allowing expansion and contraction. Step 3: Understand that true sphincters are present at the bladder neck and urethra, not as discrete circular muscles at each ureter entry. Step 4: Compare the options and select the one that states ureters are capable of peristalsis, since that is the correct anatomical fact.

Verification / Alternative check:
Anatomy textbooks describe peristaltic contractions in the ureters occurring about every 10 to 15 seconds in a hydrated adult, even when lying down. Imaging studies such as contrast radiographs show waves of contraction pushing contrast medium toward the bladder. Histology slides of ureter cross sections show transitional epithelium and multiple layers of smooth muscle, further confirming their ability to perform peristalsis and their specific lining type.

Why Other Options Are Wrong:

• Innervated only by parasympathetic fibres: The ureters receive both sympathetic and parasympathetic innervation; they are not exclusively parasympathetic.
• Contain sphincters at the entrance to the bladder: There are no well defined sphincter muscles here; prevention of reflux relies on the oblique entry and bladder wall compression.
• Epithelium is stratified squamous like the skin: This is incorrect; the ureters are lined by transitional epithelium, not by stratified squamous epithelium.

Common Pitfalls:
Students sometimes generalise that all tubes in the body have sphincters or that all epithelial linings that stretch must be similar to skin. It is important to remember that the urinary tract has a specialised epithelium called transitional epithelium and that peristalsis is characteristic of both parts of the gastrointestinal and urinary tracts. Always link ureters with peristaltic movement of urine rather than passive flow alone.

Final Answer:
The correct statement is that the ureters are capable of peristaltic contractions similar to those of the gastrointestinal tract.