Question
A 29-year-old woman comes to the physician because of poor balance and recurrent falls for the past month. She has also had blurry vision in her right eye for the past 2 weeks. She reports worsening of her symptoms after taking warm baths. Physical examination shows generalized hyperreflexia and an intention tremor. Romberg sign is positive. Visual acuity is 20/50 in the left eye and 20/100 in the right eye, and she is unable to distinguish red from green colors. The cells primarily affected by this patient’s condition are most likely derived from which of the following embryological structures?
| A. |
Mesoderm
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| B. |
Endoderm
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| C. |
Neural crest
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| D. |
Neuroectoderm
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Show Answer
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Correct Answer � D
Explanation
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Answer D) Neuroectoderm
This presentation of sudden vision problems, balance issues (e.g., Romberg sign), and worsening of neurological symptoms with increased bodily temperatures (known as the Uhthoff phenomenon) in a young woman is highly suggestive of multiple sclerosis, a demyelinating disorder of the central nervous system (CNS).
Neuroectoderm
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Neuroectoderm is the embryonic germ layer that gives rise to neurons of the CNS, astrocytes, and oligodendrocytes.
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Demyelinating disorders of the CNS are caused by injury to oligodendrocytes.
- These injuries can be caused by inflammation (e.g., multiple sclerosis as seen in this patient), infection (e.g., progressive multifocal leukoencephalopathy), nutritional disorders (e.g., subacute combined degeneration), metabolic disorders (e.g., central pontine myelinolysis), and genetic conditions (e.g., leukodystrophies).
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