In the male, the normal biota of both the urinary tract and the reproductive tract are the same. Which of the following best explains this observation?

• A. The reproductive tract is colonized by gut microbiota.
• B. Both tracts are sterile in healthy males.
• C. The distal portions of both tracts share a common passageway (the urethra).
• D. The urinary tract is colonized only after puberty.

Answer: (C)

Verified step by step guidance

1. Understand the anatomy of the male urinary and reproductive tracts, noting that both share the urethra as a common passageway for urine and semen.
2. Recognize that the presence of normal biota (microorganisms) depends on exposure to external environments or shared internal pathways where microbes can colonize.
3. Evaluate each option by considering whether it explains why both tracts have the same normal biota: for example, if both tracts are sterile, they would not share biota; if colonization occurs only after puberty, it does not explain the similarity in biota.
4. Focus on the fact that the distal portions of both tracts converge into the urethra, allowing microorganisms to colonize this shared passageway, which explains the similarity in their normal biota.
5. Conclude that the best explanation is that the distal portions of both tracts share a common passageway (the urethra), facilitating the presence of the same normal biota in both the urinary and reproductive tracts.