Lecture 33: Development of Head and Neck II

Question 1

What do the nasal placodes require for development of nose?

Answer 1

Pax6 and retinoids

Question 2

What primordium of the nose is the source of retinoids that stimulate FGF-8 to stimulate proliferation of mesenchyme and nasomedial/lateral processes?

Answer 2

Nasal pits

Question 3

From what is olfactory epithelium derived and what does it require?

Answer 3

Nasal pits; requires FGF-8

Question 4

Name the 5 stages of tooth development

Answer 4

Dental lamina, Tooth bud, Cap stage, Bell stage, Dental sac

Question 5

At what stage of tooth development do the enamel organ and dental papilla first appear at the same time?

Answer 5

Bell stage

Question 6

What cells are associated with enamel?

Answer 6

Ameloblasts

Question 7

What cells are associated with dentin?

Answer 7

odontoblasts

Question 8

What molecule is necessary for tooth development to continue past the bud stage?

Answer 8

Pax9

Question 9

Describe the action of BMP-4 during tooth development

Answer 9

Inhibits FGF-8, creates non-tooth forming spaces

Question 10

What is the effect of high [Osr-2] with regard to tooth development?

Answer 10

Suppresses tooth-inducing activity of BMP-4

Question 11

What is unique about the location of the Shh/FGF signaling during salivary gland development?

Answer 11

Occurs within the epithelium (rather than between epithelium and mesenchyme)

Question 12

Cleft lip

Answer 12

Results from lack of fusion of nasomedial and maxillary processes

Question 13

Cleft palate

Answer 13

Results from incomplete/absent fusion of palatal shelves

Question 14

Holoprosencephaly

Answer 14

Defective formation of forebrain/prosencephalon; root cause is inability of prechordal plate and anterior endoderm to secrete Shh

Question 15

Dentinogenesis imperfecta

Answer 15

Teeth appear blue-grey or amber brown and opalescent; can be non-syndromic or associated with osteogenesis imperfecta

Question 16

Amelogenesis imperfecta

Answer 16

Affects development of enamel; result in abnormalities that affect amount/composition/structure of enamel

Question 17

The facial nerve (VII) supplies muscles derived from which pharyngeal arch?

A. First
B. Second
C. Third
D. Fourth
E. Sixth

Answer 17

B. Second

Question 18

Cleft lip results from lack of fusion of the:

A. Nasomedial and nasolateral processes
B. Nasomedial and maxillary processes
C. Nasolateral and maxillary processes
D. Nasolateral and mandibular processes
E. Nasomedial and mandibular processes

Answer 18

B. Nasomedial and maxillary processes

Question 19

In cases of holoprosencephaly, defects of facial structures are typically secondary to defects in the:

A. Pharynx
B. Oral cavity
C. Forebrain
D. Eyes
E. Hindbrain

Answer 19

C. Forebrain

Question 20

Meckel’s cartilage is a prominent structure in early formation of the:

A. Upper jaw
B. Hard palate
C. Nasal septum
D. Soft palate
E. Lower jaw

Answer 20

E. lower jaw

Question 21

An early induction in tooth development consists of ectoderm of the dental epithelium acting on underlying neural crest mesenchyme. What molecule is an important mediator of this inductive stimulus?

A. BMP-4
B. Tenascin
C. Hoxb-13
D. Msx-1
E. Syndecan

Answer 21

A. BMP-4