L20: Development of Head & Neck

Question 1

early primordia for the facial region are situated around the ?

Answer 1

stomodeum

Question 2

list components of the pharyngeal region

Answer 2

pharyngeal pouches
thyroid diverticulum
pharyngeal grooves
pharyngeal arches

Question 3

pharyngeal pouches

Answer 3

4 pairs of lateral endodermal outpockets from the foregut

Question 4

thyroid diverticulum

Answer 4

ventral midline endodermal outpocketings from floor of foregut btwn pharyngeal pouches I and II

Question 5

pharyngeal grooves

Answer 5

4 pairs of ectodermal inpocketings that lie opposite to the associated pharyngeal pouches

Question 6

pharyngeal arches

Answer 6

5 pairs of mesenchymal masses

lie btwn pouches and grooves

Question 7

pharyngeal pouches – signals

Answer 7

1st - otx2
2nd - retinoic acid
3/4 - heavily dependent on retinoic acid

arch patterning is not dependent on neural crest but rather the pouches

Question 8

subdivisions of the 1st arch into upper and lower jaw primordia are dependent on ?

Answer 8

endothelin 1

Question 9

Meckel’s cartilage

Answer 9

cartilage rods developed w/in 1st arch

mandible forms around it
–forming the quadrate and articular bones (upper/lower jaw)

formation of jaw jt involves barx1

Question 10

fates of the quadrate and articular bones

Answer 10

quadrate migrates to become incus

articular migrates to become malleus

Question 11

olfactory epithelium

Answer 11

derived from dorsal epi of nasal pits
requires FGF8

forms bipolar neurons to extend to olfactory bulbs

Question 12

stages of tooth development

Answer 12

dental lamina
tooth bud
cap stage
bell stage
--enamel organ: ameloblasts
--dental papilla: odontoblasts
dental sac

Question 13

dental lamina

Answer 13

c shape bands of oral ectoderm overlying neural crest mesenchyme

Question 14

tooth bud

Answer 14

epi downgrowth of overlying neural crest mesenchyme

marks position of a single tooth

Question 15

cap stage

Answer 15

inverted cup shaped layer of ectoderm capped by stellate reticulum

covers a mass of mesenchyme = dental papilla

Question 16

bell stage

Answer 16

enamel organ
—ameloblasts make up outermost layer

dental papilla
—odontoblasts form outer layer of pulpy mass and directly under ameloblasts

Question 17

dental sac

Answer 17

a condensation of mesenchymal cells around a developing tooth

will form cementum and periodontal ligament

Question 18

relationship of msx1 and osr2 in tooth formation

Answer 18

bmp4 causes msx1 expression which causes the development of an extra tooth

osr2 inhibits bmp4 so msx1 cannot be expressed

Question 19

salivary gland development depends heavily on ?

Answer 19

shh

and also FGF