Embryology of the Eye

Question 1

what two tissues form the eye

Answer 1

ectoderm (neural and surface) and mesenchyme

Question 2

what is responsible for the development of many ocular structures

Answer 2

induction

Question 3

what are the 3 germ layers in development

Answer 3

ectoderm (outer), mesoderm (middle), and endoderm (inner)

Question 4

what do the 3 germ layers form

Answer 4

the embryonic plate

Question 5

what is the neural groove

Answer 5

a longitudinal groove that forms down the neural plate, where the neural folds form from

Question 6

what does the neural plate give rise to

Answer 6

the central nervous system and eye

Question 7

what is the neural tube made of

Answer 7

neural ectoderm

Question 8

what surrounds the neural ectoderm

Answer 8

mesoderm (covered by neural ectoderm on the dorsal side)

Question 9

what are the 2 kinds of ectoderm

Answer 9

neural and surface

Question 10

what are the neural crest cells

Answer 10

when the neural folds are moving towards another to fuse, these cells form and become specialized between the neural tube and surface ectoderm (in the mesoderm)

Question 11

what is mesenchyme

Answer 11

includes mesoderm and neural crest cells

Question 12

what are the optic pits

Answer 12

small depressions that form as the neural tube is closing

Question 13

what are the optic vesicles

Answer 13

when the optic pits begin to form outer pits that extend from the lateral aspect of the forebrain

Question 14

what is the optic stalk

Answer 14

the proximal portion of each optic vesicle near the forebrain begins to constrict and form the optic stalk

Question 15

what is continuous with the 3rd ventricle of the brain

Answer 15

a cavity inside the optic vesicle and optic stalk

Question 16

what is the inferior optic fissure

Answer 16

the opening of the optic stalk that allows the Hyaloid vasculature to enter the stalk, it will then close after

Question 17

what is the inferior optic fissure called after it closes

Answer 17

optic canal

Question 18

what structures come from the optic cup inner layer

Answer 18

neural retina, non-pigmented ciliary epithelium, iris posterior pigmented epithelium

Question 19

what structures come from the optic cup outer layer

Answer 19

RPE, pigmented ciliary epithelium, iris anterior pigmented epithelium

Question 20

what is induction

Answer 20

the influence a structure has on another structure

Question 21

what is the lens plate or lens placode

Answer 21

when the optic vesicle was in contact with the surface ectoderm, the surface ectoderm thickens to form it

Question 22

what does the lens plate form

Answer 22

it elongates and invaginates to for the lens pit and then closes to form the lens vesicle

Question 23

what happens to the lens vesicle to form the embryologic nucleus

Answer 23

the posterior epithelial cells elongate anteriorly to fill the cavity and are now referred to as primary lens fibers

Question 24

what form the lens bow

Answer 24

the primary epithelial cells move anteriorly and form a bow (no sutures yet)

Question 25

what do the first set of secondary lens fibers form

Answer 25

they surround the embryonic nucleus and meet as anterior upright Y sutures and posterior inverted Y sutures

Question 26

what will remain if the hyaloid vasculature does not fully resorb by birth

Answer 26

Bergmeisters papilla and Mittendorf's dot

Question 27

what does the Hyaloid vasculature give rise to

Answer 27

the central retinal artery and vein

Question 28

what does the developing RPE induce to form

Answer 28

choriocapillaries from the mesenchyme

Question 29

which layer pigmented or nonpigmented ciliary epithelium forms the ciliary processes

Answer 29

the pigmented form the processes and the NPE follow

Question 30

when is aqueous humor produced

Answer 30

around 4-6 months of gestation

Question 31

where is the ciliary body stroma made from

Answer 31

neural crest cells

Question 32

where is the ciliary muscle derived from

Answer 32

mesenchyme

Question 33

where does the iris come from

Answer 33

the rim of the optic cup, between the lens and cornea

Question 34

where are the iris sphincter and dilator from

Answer 34

neural ectoderm (only muscles that are)

Question 35

what is the iris stroma formed from

Answer 35

mesenchyme

Question 36

where does the pupillary membrane form

Answer 36

between the lens epithelium and the corneal endothelium

Question 37

what is the pupillary membrane made from

Answer 37

transient structure from mesenchyme, resorbed by birth

Question 38

how do the anterior and posterior chambers form

Answer 38

they develop as slits and eventually communicate when the pupillary membrane disappears

Question 39

what is trabecular meshwork derived from

Answer 39

mesenchyme

Question 40

what is schlemms canal derived from

Answer 40

deep scleral plexus

Question 41

what does the fibrilar material secreted by embryonic retina and ectodermal cells of the lens form

Answer 41

the primary vitreous

Question 42

when does the secondary vitreous form

Answer 42

as the optic cup continues to increase in size

Question 43

where does the secondary vitreous come from

Answer 43

neural retina and degenerating hyaloid vasculature

Question 44

what is the first layer of the retina to form

Answer 44

the RPE

Question 45

what is the retina formed from

Answer 45

the inner layer of the optic cup

Question 46

what area of the retina is the first to form

Answer 46

the macular area, the thickest area for awhile

Question 47

what is the last portion of the retina to fuly develop

Answer 47

the foveola

Question 48

what induces the formation of the cornea

Answer 48

the lens vesicle

Question 49

what is the corneal epithelium derived from

Answer 49

surface ectoderm

Question 50

what is the corneal endothelium derived from

Answer 50

neural crest cells

Question 51

what is the corneal stroma derived from

Answer 51

mesenchyme

Question 52

what is the sclera derived from

Answer 52

condensations of mesenchyme outside the optic cup

Question 53

how do the eyelids develop

Answer 53

as folds (epithelial buds) of surface ectoderm, filled with mesenchyme

Question 54

are the eyelids fused together until they are fully developed

Answer 54

yes