Embryology: sexual differentiation: practice question

A Anatomy 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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Anatomy · Embryology: sexual differentiation

Sample item

At herniorrhaphy in an infant with male external genitalia, a uterus and fallopian tubes are found in the hernial sac, and the karyotype is 46,XY with normal testes. Which deficiency explains this?

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

The answer and the reasoning

D. Anti-Mullerian hormone or its receptor

The SRY gene on the Y chromosome drives testis formation. Sertoli cells then secrete anti-Mullerian hormone, which makes the paramesonephric ducts regress, while Leydig cell testosterone preserves the Wolffian derivatives. Deficient anti-Mullerian hormone or receptor leaves the uterus and tubes, with normal male virilisation (persistent Mullerian duct syndrome).

Option by option

  • A. The SRY gene

    SRY loss produces gonadal dysgenesis without testes, which are normal in this case.

  • B. 5-alpha reductase type 2

    Deficiency of 5-alpha reductase gives ambiguous external genitalia with blind vagina but no uterus.

  • C. Testosterone synthesis

    Failure of testosterone synthesis would impair male external genital development, and Wolffian ducts would be poorly developed.

  • D. Anti-Mullerian hormone or its receptor (correct)

    Correct. Failure of Mullerian regression with normal testes and virilisation is persistent Mullerian duct syndrome.

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.

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Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is D, Anti-Mullerian hormone or its receptor. The SRY gene on the Y chromosome drives testis formation.

Why is "The SRY gene" not the answer?

SRY loss produces gonadal dysgenesis without testes, which are normal in this case.

Why is "5-alpha reductase type 2" not the answer?

Deficiency of 5-alpha reductase gives ambiguous external genitalia with blind vagina but no uterus.

Why is "Testosterone synthesis" not the answer?

Failure of testosterone synthesis would impair male external genital development, and Wolffian ducts would be poorly developed.

What concept does this question test?

It tests Embryology: sexual differentiation in Anatomy. Sertoli cells then secrete anti-Mullerian hormone, which makes the paramesonephric ducts regress, while Leydig cell testosterone preserves the Wolffian derivatives. Deficient anti-Mullerian hormone or receptor leaves the uterus and tubes, with normal male virilisation (persistent Mullerian duct syndrome).

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Embryology: sexual differentiation?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy 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.