Lecture 14

Question 1

The ______ skeleton is a continuous interaction between apical ectodermal ridge and limb bud mesoderm

Answer 1

limb

Question 2

The ______ ______ is an inductive interaction between sclerotome and notochord or neural tube

Answer 2

vertebral column

Question 3

The ____ interacts between preskeletal neural crest cells and information along migratory paths and interacts between areas of the brain and overlying mesenchyme

Answer 3

head

Question 4

Describe the common bone/cartilage differentiation pathway

Answer 4

• mesenchyme is induced to enter common pathway
• production of N cadherins which promote mesenchymal cell condensation
• TGF-B stimulates synthesis of fibronectin and N-CAM
• aggregated state of mesenchymal cells is stabilized

Question 5

Describe the membranous bone pathway

Answer 5

• requires transcription factors Runx-2 and Osx

- mesenchymal cells differentiate into osteoblasts

Question 6

Describe the permanent cartilage pathway

Answer 6

• mesenchymal condensation forms chondroblasts
• sox-9 causes chondroblasts to secrete collagen II and cartilage matrix
• sox-9 is continually expressed in permanent cartilage

Question 7

Describe the endochondral bone pathway

Answer 7

• Runx-2, ihh, and BMP-6 induce this cartilage to undergo hypertrophy
• hypertrophic cartilage cells secrete bone proteins and vascular endothelial growth factor
• invading blood vessels erode the hypertrophic cartilage and bring in osteoblasts to replace cartilage with bone

Question 8

Where is the centrum derived from

Answer 8

ventral and medial parts of paired sclerotomes

Question 9

Where do the neural arches arise from?

Answer 9

dorsal regions of sclerotomes

Question 10

The proximal development of the costal processes/ribs depends on expression of myotonic myogenic factors, ____ and____

Answer 10

Myf-5 and Myf-6

Question 11

Distal development of the costal processes/ribs depends on ____ signals from somotaopleural mesoderm

Answer 11

BMP

Question 12

the sternum is derived from the _______

Answer 12

lateral plate mesoderm

Question 13

Where does the clavicle arise from?

Answer 13

neural crest

Question 14

What is the neurocranium?

Answer 14

part of skull that surrounds the brain

Question 15

what is the viscerocranium?

Answer 15

surrounds oral cavity and pharynx

Question 16

Viscerocranium is mostly comprised of ______ arches

Answer 16

branchial (pharyngeal)

Question 17

What are the four components of each pharyngeal arch?

Answer 17

skeletal elements
muscles
a branch of a specific cranial nerve
artery

Question 18

elongation of primary ossification centers is due to ____

Answer 18

Shh

Question 19

occipital cervical boundary

Answer 19

hox 3

Question 20

cervical thoracic boundary

Answer 20

hox 6

Question 21

attached floating ribs boundary

Answer 21

hox 9

Question 22

what is one of the first bones to become ossified?

Answer 22

the clavicle

Question 23

What pathway does the development of the clavicle follow?

Answer 23

intramembranous

Question 24

What does the cartilaginous portion of the viscerocranium form?

Answer 24

pharyngeal arch I and II

Question 25

What does the membranous portion of the viscerocranium form?

Answer 25

part of temporal, zygomatic, maxillary, nasal, lacrimal, palatine, vomer, pterygoid plates, mandible, tympanic ring

Question 26

the basioccipital portion of chondrocranium is derived from ______ and ___

Answer 26

parachordal cartilages and occipital sclerotomes

Question 27

elongation of primary ossification center is due to ___

Answer 27

Shh

Question 28

what is the result of inductive interactions of surround mesenchyme?

Answer 28

bones of the neurocranium arise,