NP3B

Question 1

an extremely rare disorder of the central nervous system in which a cyst or cavity filled with cerebrospinal fluid develops in the brain

Answer 1

porencephaly

Question 2

Why does the cerebrum form sulci and gyri?

Answer 2

to increase GM surface and volume

Question 3

Decreased grey matter formation (cortical hypoplasia) is reflected in a reduced number of:

Answer 3

• gyri (pachygyria)
• even the complete absence of gyri (lissencephaly)

Question 4

Rabbits and manatees are normally _______________, and birds don’t develop a cerebral cortex.

Answer 4

lissencephalic

Question 5

is the result of a radiomimetic agent that kills cells in a structure whose development is well under way.

Answer 5

Porencephaly

Question 6

The case illustrated here is a lamb that was infected late in gestation with:

Answer 6

Bluetongue virus

Question 7

Defects in myelin range from failure to form, delayed formation, or abnormal formation of myelin. The outcome is the same:

Answer 7

failure to support neuronal salutatory conduction

Question 8

refers to malformed and defective myelin sheath as opposed to the destruction of previously normal myelin that is seen in demyelination

Answer 8

dysmyelination

Question 9

hypomyelinogenesis and dysmyelinogenesis: Many of these disorders are heritable, and here it is important to remember that oligodendrocytes and Schwann cells both produce myelin, but they use distinct molecules to achieve this. As such, heritable defects will be specific to the:

Answer 9

central or peripheral nervous system

Question 10

Heritable hypomyelinogenesis and dysmyelinogenesis, keys to consider:

Answer 10

• evident early in life
• lesions are symmetrical and may or may not require histological evaluation to recognize
• lack of myelin is not associated with accumulation of gitter cells – gitter cells reflect demyelination

Question 11

Acquired hypomyelinogenesis, Border disease virus of sheep:

Answer 11

This virus infects lambs late during gestation, and causes severe diffuse hypomyelination without ever stepping foot inside the central nervous system.

Question 12

Which thyroid hormone does oligodendrocytes require to form myelin?

Answer 12

T3 and T4

Question 13

Thyroid hormone induces __________, an enzyme in oligodendrocytes that links
cytoskeleton to cellular membranes

Answer 13

CNPase (2’3’ cyclic nucleotide phosphodiesterase)

Question 14

Infection of ewes during mid-gestation with Border disease virus causes infection
of thyroid follicular epithelial cells of the fetus, decreasing fetal T3 and T4
production, and resulting in marked:

Answer 14

hypomyelinogenesis

Question 15

Copper (Cu) deficiency in utero is:

Answer 15

acquired hypomyelinogenesis

Question 16

Functions that are necessary for myelin formation and for the neuron to support axons.

Answer 16

• Cytochrome oxidase
• Superoxide dismutase

Question 17

energy metabolism and phospholipid synthesis

Answer 17

Cytochrome oxidase

Question 18

protection against free radicals

Answer 18

Superoxide dismutase

Question 19

You might only see hypomyelinogenesis, or you might see both hypomyelinogenesis and failure of neurons to support axons. In the extreme, large cavities can form where cerebral white matter should have been (porencephaly)

Answer 19

Copper (Cu) deficiency in utero - Swayback

Question 20

changes are restricted to select tracts in the spinal cord, representing hypomyelination and possibly Axon Degeneration.

Answer 20

Copper (Cu) Post-natal deficiency - Enzootic ataxia

Question 21

What describes heritable hypomyelinogenesis?

Answer 21

the changes will occur either in the CNS or PNS, and lack of myelin will not be associated with gitter cell formation

Question 22

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