Development of the Musculoskeletal System (Embryology)

Question 1

The neural tube is derived from what germ layer?

Answer 1

Ectoderm

Question 2

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

Answer 2

PNS

Question 3

Somites are derived from what germ layer?

Answer 3

mesoderm

Question 4

What type of cells are in the early notchord?

Answer 4

undifferentiated neuroepithelial cells; they are pseudostratified and highly mitotic.

Question 5

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

Answer 5

neural and glial progenitor cells

Question 6

What do neuroglia cells do?

Answer 6

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

Question 7

What does the marginal layer contain?

Answer 7

neuronal processes (axons)

Question 8

Where do postmitotic neurons and glioblasts migrate towards?

Answer 8

the intermediate mantle/cortical zone.

Question 9

What does the intermediate mantle/cortical zone contain?

Answer 9

inner gray matter (neuronal cell bodies and microglia).

Question 10

What does the marginal zone contain?

Answer 10

myelinated neuronal proceses (axons).

Question 11

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

Answer 11

BMP 4 and 7.

Question 12

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

Answer 12

Shh (sonic hedgehog)

Question 13

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

Answer 13

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

Question 14

What are the 3 divisions of the mesoderm?

Answer 14

paraxial, intemediate and lateral

Question 15

What does the paraxial mesoderm give rise to?

Answer 15

axial skeleton and ALL skeletal muscle

Question 16

What does the intermediate mesoderm give rise to?

Answer 16

kidneys and gonads (urogential system).

Question 17

What does the lateral plate mesoderm give rise to?

Answer 17

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

Question 18

What is the paraxial mesoderm?

Answer 18

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

Question 19

What genes regulate growth/differentiation in the head?

Answer 19

hox genes

Question 20

What is segmentation controlled by?

Answer 20

pulses of gene expression.

Question 21

What does the somite of the paraxial mesoderm differentiate into?

Answer 21

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

Question 22

What is the function of notch?

Answer 22

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

Question 23

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

Answer 23

increases, decreases

Question 24

What is the function of retinoic acid?

Answer 24

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.

Question 25

Where is retinoic acid expression the highest?

Answer 25

in caudal regions.

Question 26

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

Answer 26

higher

Question 27

What does the somite divide into?

Answer 27

sclerotome, dermatome and myotome.

Question 28

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

Answer 28

sclerotome; they move medially and surround the notochord.

Question 29

Cells facing the surface ectoderm differentiate into what?

Answer 29

the dermomyotome.

Question 30

What is resegmentation?

Answer 30

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

Question 31

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

Answer 31

vertebrae

Question 32

What does the notochord form in the intervertebral disc?

Answer 32

the nucleus pulposus

Question 33

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

Answer 33

mutliple.

Question 34

What kinds of muscle does the myotome create?

Answer 34

epaxial (dorsal) and hypaxial (ventral).

Question 35

What are MyoD and MYF5?

Answer 35

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

Question 36

What would happen if MyoD and MYF5 were not present?

Answer 36

Differentiation into hypaxial and epaxial muscles would not occur.

Question 37

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

Answer 37

myotomes

Question 38

What does the lateral plate segment into?

Answer 38

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.

Question 39

What is another term for the exterior lateral plate?

Answer 39

somatic mesoderm

Question 40

What is another term for the interior lateral plate?

Answer 40

splanchnic mesoderm