Histo Flashcards

1
Q

The central nervous system (CNS) appears at

A

the beginning of the third week

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2
Q

The CNS starts as

A

the neural plate

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3
Q

the neural plate and it’s location

A

slipper shaped plate of thickened ectoderm located in the mid- dorsal region in front of the primitive node.

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4
Q

the neural plate lateral edges elevate to form

A

neural folds.

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5
Q

With further development, the neural

folds

A

continue to elevate,

other in the midline, and finally fuse, forming the neural tube.

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6
Q

How is the neural tube formed

A

When the lateral edges of neural plate elevate to neural folds which continue to elevate and then approach each other in the middle of the

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7
Q

Fusion of neural fold begins in

A

cervical region

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8
Q

Once fusion is initiated, the open ends of the neural tube form

A

the cranial and caudal neuropores

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9
Q

the cranial and caudal neuropores functions

A

communicate with the overlying amniotic cavity.

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10
Q

Closure of the cranial neuropore proceeds in what location

A

cranially from the initial closure site in the cervical region and from a site in the forebrain that forms later.

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11
Q

Final closure of the cranial neuropore occurs at …..closure of the caudal neuropore occurs approximately ……

A

the 18 to 20-somite stage (25th day);

3 days later (28th day).

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12
Q

cephalic end of the neural tube shows three dilations

A

(1) the prosencephalon, or forebrain;
(2) the mesencephalon, or midbrain; and
(3) the rhombencephalon, or hindbrain.

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13
Q

Simultaneously, the cephalic end of neural tube forms two flexures:

A

1) the cervical flexure

2) the cephalic flexure

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14
Q

the cervical flexure location

A

at the junction of the hindbrain and the

spinal cord

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15
Q

the cephalic flexure location

A

in the midbrain region.

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16
Q

When the embryo is 5 weeks old, the prosencephalon consists of two parts:

A

telencephalon

Diencephalon

17
Q

telencephalon is formed by

A

a midportion and two lateral outpocketings: the primitive cerebral hemispheres

18
Q

Diencephalon is characterised by

A

outgrowth of the optic vesicles, pituitary, epiphysis etc.

19
Q

rhombencephalon (hind brain) also consists of two parts

A

metencephalon

myelencephalon

20
Q

metencephalon later forms

A

pons and cerebellum

21
Q

myelencephalon later forms

A

medulla oblangata.

22
Q

The boundary between metencephalon and myelencephalon is marked by

A

pontine flexure.

23
Q

What separates the mesencephalon from the rhombencephalon.

A

rhombencephalic isthmus (a deep furrow)

24
Q

The lumen of the spinal cord, the central canal, is continuous with

A

that of the brain vesicles.

25
Q

fourth ventricle

A

The cavity of the rhombencephalon

26
Q

third ventricle,

A

Cavity of diencephalon

27
Q

lateral ventricles.cavities of

A

cerebral hemispheres

28
Q

What connects the third and fourth ventricles?

A

The lumen of the mesencephalon

29
Q

When lumen of mesencephalon becomes very narrow and is then known as

A

aqueduct of Sylvius.

30
Q

Each lateral ventricle communicates with the third ventricle through

A

interventricular foramina of Monro