Reproduction: duration of spermatogenesis: 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 · Reproduction: duration of spermatogenesis

Sample item

A 30-year-old man has a sperm count of 3 million/mL during sulfasalazine therapy, which is then stopped. About when should a repeat semen analysis be done to judge recovery?

AAfter about 3 months, because spermatogenesis takes about 74 days plus epididymal transitBAfter 12 months, because spermatogenesis takes about a yearCAfter 1 week, because spermatids mature in a few daysDAfter 4 weeks, because spermatogenesis takes one menstrual cycle

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

The answer and the reasoning

A. After about 3 months, because spermatogenesis takes about 74 days plus epididymal transit

One cycle of spermatogenesis from spermatogonium to spermatozoon in the seminiferous tubule takes about 74 days, followed by roughly 10 to 14 days of epididymal transit. Any effect of a toxin or drug on sperm production therefore needs at least 2 to 3 months to show recovery.

Option by option

A. After about 3 months, because spermatogenesis takes about 74 days plus epididymal transit (correct)
Correct. About 3 months covers the cycle and transit.
B. After 12 months, because spermatogenesis takes about a year
A year is more than the 74-day cycle and transit time.
C. After 1 week, because spermatids mature in a few days
A week is far shorter than the time for germ cell maturation.
D. After 4 weeks, because spermatogenesis takes one menstrual cycle
Spermatogenesis is not tied to the menstrual cycle and takes longer than 4 weeks.

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 A, After about 3 months, because spermatogenesis takes about 74 days plus epididymal transit. One cycle of spermatogenesis from spermatogonium to spermatozoon in the seminiferous tubule takes about 74 days, followed by roughly 10 to 14 days of epididymal transit.

Why is "After 12 months, because spermatogenesis takes about a year" not the answer?

A year is more than the 74-day cycle and transit time.

Why is "After 1 week, because spermatids mature in a few days" not the answer?

A week is far shorter than the time for germ cell maturation.

Why is "After 4 weeks, because spermatogenesis takes one menstrual cycle" not the answer?

Spermatogenesis is not tied to the menstrual cycle and takes longer than 4 weeks.

What concept does this question test?

It tests Reproduction: duration of spermatogenesis in Physiology. Any effect of a toxin or drug on sperm production therefore needs at least 2 to 3 months to show recovery.

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 Reproduction: duration of spermatogenesis?

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.