Development of the Musculoskeletal System (Embryology) Flashcards

1
Q

The neural tube is derived from what germ layer?

A

Ectoderm

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2
Q

What component of the nervous system to neural crest cells form?

A

PNS

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3
Q

Somites are derived from what germ layer?

A

mesoderm

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4
Q

What type of cells are in the early notchord?

A

undifferentiated neuroepithelial cells; they are pseudostratified and highly mitotic.

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5
Q

Division of the neuroepithelial cells in the neural tube gives rise to what 2 kinds of cells?

A

neural and glial progenitor cells

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6
Q

What do neuroglia cells do?

A

Support cells of the CNS. They insulate, nourish and protect neurons.

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7
Q

What does the marginal layer contain?

A

neuronal processes (axons)

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8
Q

Where do postmitotic neurons and glioblasts migrate towards?

A

the intermediate mantle/cortical zone.

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9
Q

What does the intermediate mantle/cortical zone contain?

A

inner gray matter (neuronal cell bodies and microglia).

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10
Q

What does the marginal zone contain?

A

myelinated neuronal proceses (axons).

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11
Q

What does the ectoderm secrete (it is also eventually secreted by the dorsal portion of the neural tube?)

A

BMP 4 and 7.

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12
Q

What does the notochord secrete (it is also eventually secreted by the ventral portion of theneural tube?)

A

Shh (sonic hedgehog)

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13
Q

BMP4, 7, and Shh create what in the neural tube?

A

A gradient; it tells what kinds of neurons will be developed in particular parts of the tube.

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14
Q

What are the 3 divisions of the mesoderm?

A

paraxial, intemediate and lateral

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15
Q

What does the paraxial mesoderm give rise to?

A

axial skeleton and ALL skeletal muscle

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16
Q

What does the intermediate mesoderm give rise to?

A

kidneys and gonads (urogential system).

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17
Q

What does the lateral plate mesoderm give rise to?

A

connective tissue, skeleton of the llimbs, sooth muscle/connective tissue of blood vessels.

18
Q

What is the paraxial mesoderm?

A

A “segmented” series of tissue blocks on each side of the neural tube. It contains somitomeres (head) and somites (spinal cord)

19
Q

What genes regulate growth/differentiation in the head?

A

hox genes

20
Q

What is segmentation controlled by?

A

pulses of gene expression.

21
Q

What does the somite of the paraxial mesoderm differentiate into?

A

sclerotome (cartilage), dermotome (dermis), myotome (muscle)

22
Q

What is the function of notch?

A

activates other segment-patterning genes in the somites.it helps to break up somites.

23
Q

Notch expression ___ in somites destined to be formed and ___ in already-developed somites.

A

increases, decreases

24
Q

What is the function of retinoic acid?

A

It sets up boundaries for somites, and works with notch to cut off regions of segmentation. It also controls the segmentation clock and activity of notch.

25
Q

Where is retinoic acid expression the highest?

A

in caudal regions.

26
Q

Animals with extensive vertebrae (e.g. a snake) generally have a ____ level of gene activity.

A

higher

27
Q

What does the somite divide into?

A

sclerotome, dermatome and myotome.

28
Q

Which region of the somite is closest to the neural tube?

A

sclerotome; they move medially and surround the notochord.

29
Q

Cells facing the surface ectoderm differentiate into what?

A

the dermomyotome.

30
Q

What is resegmentation?

A

The segmentation of sclerotome segments into caudal and rostral halves; they eventually fuse to form vertebrae.

31
Q

What do the caudal and rostral halves of the sclerotome eventually form?

A

vertebrae

32
Q

What does the notochord form in the intervertebral disc?

A

the nucleus pulposus

33
Q

A type of vertebrae a somite becomes i s controlled by ___ hox genes.

A

mutliple.

34
Q

What kinds of muscle does the myotome create?

A

epaxial (dorsal) and hypaxial (ventral).

35
Q

What are MyoD and MYF5?

A

Transcription factors that signal the development of epaxial and hypaxial muscles.

36
Q

What would happen if MyoD and MYF5 were not present?

A

Differentiation into hypaxial and epaxial muscles would not occur.

37
Q

Spinal nerves from the neural tube innervate what derivative of the paraxial mesoderm?

A

myotomes

38
Q

What does the lateral plate segment into?

A

A region that forms the gut, and a region that forms the outer body wall. The region that forms the outer body wall will surround and trap the gut region.

39
Q

What is another term for the exterior lateral plate?

A

somatic mesoderm

40
Q

What is another term for the interior lateral plate?

A

splanchnic mesoderm