Embryology: neural crest disorders: 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: neural crest disorders

Sample item

A child has a white forelock, irises of different colours and sensorineural deafness. Disturbed development of which embryonic cell population explains these findings?

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

The answer and the reasoning

A. Neural crest cells

In Waardenburg syndrome, neural crest-derived melanocytes fail to migrate or survive, causing depigmented hair, iris heterochromia and cochlear pigment cell loss with deafness.

Option by option

  • A. Neural crest cells (correct)

    Correct. Neural crest cells give rise to melanocytes, including those of the hair, iris and inner ear.

  • B. Surface ectoderm

    Surface ectoderm forms the epidermis and lens but not melanocytes.

  • C. Paraxial mesoderm

    Paraxial mesoderm forms somites and does not give rise to melanocytes.

  • D. Endoderm

    Endoderm forms gut and respiratory epithelium and has no melanocyte contribution.

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 A, Neural crest cells. In Waardenburg syndrome, neural crest-derived melanocytes fail to migrate or survive, causing depigmented hair, iris heterochromia and cochlear pigment cell loss with deafness.

Why is "Surface ectoderm" not the answer?

Surface ectoderm forms the epidermis and lens but not melanocytes.

Why is "Paraxial mesoderm" not the answer?

Paraxial mesoderm forms somites and does not give rise to melanocytes.

Why is "Endoderm" not the answer?

Endoderm forms gut and respiratory epithelium and has no melanocyte contribution.

What concept does this question test?

It tests Embryology: neural crest disorders in Anatomy. The correct option holds because: Correct. Neural crest cells give rise to melanocytes, including those of the hair, iris and inner ear.

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 Embryology: neural crest disorders?

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.