Exam 2 10/23 Genetic Control of Tooth Development

Question 1

Root cementum development

Answer 1

Dental follicle cells migrate in and contact new root dentin surface, differentiate into cementoblasts which secrete cementoid

Question 2

Cementoid mineralizes into ____ in apposition to ____

Answer 2

cementum; root dentin

Question 3

Alveolar process formation begins in:

Answer 3

8th week

Question 4

Eruptive tooth movements of primary teeth are:

Answer 4

Axial or occlusal

Question 5

What growth factors drive thickening of oral epithelium where tooth will form, and what inhibits it?

Answer 5

Drivers: FGF, Wnt, Shh
Inhibitor: BMP
Ensures no unitooth

Question 6

If WNT is blocked at initiation of tooth formation, what happens?

Answer 6

No tooth develops

Question 7

When dental lamina epithelial cells thicken, they secrete:

Answer 7

FGF-8

Question 8

FGF8 drives expression of:

Answer 8

Lhx-6, Lhx-7 which activate in surrounding ectomesenchymal cells

Question 9

Any gene that controls organ development:

Answer 9

Homeobox gene

Question 10

FGF8 induces ____ in the exact sites along primary epithelial band where teeth will form

Answer 10

Pax9
(also Shh)

Question 11

Pax9 is inhibited by

Answer 11

BMP 2 and 4

Question 12

Neural crest cells condense in response to:

Answer 12

FGF8

Question 13

Mutations associated with tooth agenesis (excluding third molars)

Answer 13

Pax9 and Shh

Question 14

Lef-1

Answer 14

Expressed first in dental lamina/bud stage, then switches to ectomesenchyme

Question 15

What does Lef-1 do?

Answer 15

Reciprocal switch

Question 16

What genes are expressed in condensing EMC that if removed, never advance past bud stage?

Answer 16

Pax9, Msx1

Question 17

___ drives BMP 4 expression by condensing mesenchyme

Answer 17

Msx1

Question 18

BMP4 drives continued expression of:

Answer 18

Msx1 (loop that drives further condensation/differentiation to develop dental papilla)