Devlopment L8 - oral developmental biology Odontogenesis 2

Question 1

what is the name of the epitheliums that line the periphery of the enamel organ

Answer 1

inner and outer enamel epithelium

Question 2

during the bell stage the inner enamel epithelium cells differentiate and become tall columnar what?

Answer 2

pre-ameloblasts

Question 3

some cells between the inner enamel epithelium and stellate reticulum become spindle shaped forming which cell?

Answer 3

stratum intermedium

Question 4

the cervical loop is continuation of the inner and outer enamel epithelium.

the cervical loop is an part of the tooth germ in that, it gives rise to the?

Answer 4

dental papilla and dental follicle

Question 5

growth factors released from the cervical loop during the early stages of bell stage differnetiate the mesenchyme cells in to which cells?

Answer 5

dental papilla

Question 6

growth factors released from the cervical loop allow the Dental Papilla and the Inner enamel epithelium to mature, causing them to elongate and polarise.

this allows the Dental Papilla to invade the acellular zone.

what does the dental papilla mature in to

Answer 6

mature in to odontoblasts to form predentine then dentine

Question 7

IEE cells mature in to what?

Answer 7

Ameloblasts to form enamel

Question 8

once dentine has been laid down near the cusp, what does this activate?

Answer 8

the laying of dentine signals ameloblast to lay down enamel.

Question 9

the most cervical (cervical loop) portion of the enamel organ is responsible for the development of what?

Answer 9

root development

Question 10

bell stage is marked by two events called morphodifferentiation and histodifferentiation which happen simultaneously.

what is morphdifferentiation and histodifferentiation?

Answer 10

morphodifferentiation refers to the establishment of the shape of the crown

histodifferentiation refers to the “coming of age” moment when dental papilla cells differentiate to odontoblast and inner enamel epithelial cells become ameloblasts

Question 11

once the crown has been formed, the cercical loop starts to proliferate to give rise to what

Answer 11

hertwig’s epithelial root sheath.

the rooth sheath bends at 45 degrees towards the pulp narrowing the cervical opening.

Question 12

as the root sheath proliferates, the inner layer of the root sheath induces differentiation.

the differentiation causes adjacent dental papilla cells to odontblasts which then produce the dentine.

what affect does dentine have on the root sheath

Answer 12

as dentine is formed, it begins to minerlaise and disintergrate the adjacent rooth sheath?

Question 13

with the disintegration of the root sheath, gives access to dental folllicle cells to invade and interact with the dentine.

this interaction allows the follicle cells to differentiate to which cells

Answer 13

dental follicle cells differentiate to cementoblasts and lay down cementum

Question 14

the image shows a devloping tooth at late bell stage:

a layer of pre-dentine is forming and this will stimulate what?

Answer 14

the ameloblasts to synthesise and secrete enamel proteins

Question 15

odontoblast differentiate to become columnar in shape why is this?

Answer 15

odontoblast are protein secreting cells and the shape accomodates the abundance of rough ER and Golgi

Question 16

the initial enamel secreting cells formed are responsible for the formation of what?

Answer 16

for the formation the enamel-dentine junction

Question 17

once ameloblast have matured, what happens to the cell size

Answer 17

once matured cells regress in height to protect enamel surface

Question 18

image e

the red coloured stain shows what

the purple coloured stain identified as E shows what

Answer 18

red coloured stain shows dentine

purple coloured stain shows enamel

Question 19

pre-dentine is an organic matrix that makes up dentine before it is calcified. what collagens make up pre-dentine

Answer 19

collagen I, III, V, VI

Question 20

enamel is made up of two groups of protein what are their names

Answer 20

amelogenins - make up 90-95%

enamelins - make up 5-10%

Question 21

tooth chape determination is determined by the maturation and division of what

Answer 21

IEE cell division and IEE cell maturation

Question 22

what role does reduced enamel epithelium play

Answer 22

protection of enamel surface from resoprtion

provide and epithelial lined pathway for eruption

forms initial junctional epithelium