Male reproductive physiology: feedback: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Male reproductive physiology: feedback

Sample item

A 24-year-old bodybuilder using exogenous testosterone has small, soft testes and a very low sperm count. His serum LH and FSH are low. What is the mechanism?

AIncreased inhibin B from Sertoli cellsBPositive feedback increases LH and FSH releaseCNegative feedback suppresses GnRH and gonadotropin release, reducing spermatogenesisDDirect toxic destruction of Leydig cells

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. Negative feedback suppresses GnRH and gonadotropin release, reducing spermatogenesis

Exogenous androgens act on the hypothalamus and pituitary to suppress GnRH, LH and FSH. Without LH, the Leydig cells make little testosterone, so intratesticular testosterone, which is required for spermatogenesis, falls. The testes atrophy and sperm production declines.

Option by option

A. Increased inhibin B from Sertoli cells
Inhibin B would fall with reduced spermatogenesis, not rise.
B. Positive feedback increases LH and FSH release
Positive feedback does not apply to male gonadal steroids.
C. Negative feedback suppresses GnRH and gonadotropin release, reducing spermatogenesis (correct)
Correct. Feedback suppression of gonadotropins reduces testicular function.
D. Direct toxic destruction of Leydig cells
The Leydig cells are suppressed functionally, not destroyed.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is C, Negative feedback suppresses GnRH and gonadotropin release, reducing spermatogenesis. Exogenous androgens act on the hypothalamus and pituitary to suppress GnRH, LH and FSH.

Why is "Increased inhibin B from Sertoli cells" not the answer?

Inhibin B would fall with reduced spermatogenesis, not rise.

Why is "Positive feedback increases LH and FSH release" not the answer?

Positive feedback does not apply to male gonadal steroids.

Why is "Direct toxic destruction of Leydig cells" not the answer?

The Leydig cells are suppressed functionally, not destroyed.

What concept does this question test?

It tests Male reproductive physiology: feedback in Physiology. Without LH, the Leydig cells make little testosterone, so intratesticular testosterone, which is required for spermatogenesis, falls. The testes atrophy and sperm production declines.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Male reproductive physiology: feedback?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.