Embryology

Question 1

what fibers are included in the fetal nucleus

Answer 1

contains all fibers before birth

Question 2

what type of fibers are in the fetal nucleus

Answer 2

secondary fibers

Question 3

how does the embryonic nucleus form?

Answer 3

posterior epi elongates to fill the lumen

formation of the lens bow

Question 4

what type of fibers are in the embryonic nucleus?

Answer 4

primary lens fibers

Question 5

when do the eyelids fuse and separate?

Answer 5

fuse: month 3
separate: month 5-6

Question 6

lacrimal system: surface ectoderm

Answer 6

nasolacrimal drainage system

Question 7

what is a coloboma?

Answer 7

incomplete closure of fetal fissure in the inferior and nasal aspect

Question 8

when does the optic cup elongates between the lens + cornea

Answer 8

month 3

Question 9

what structures can be involved in an coloboma

Answer 9

optic disc, iris, retina, cb, optic nerve

Question 10

what structures in the iris are formed from neural ectoderm

Answer 10

anterior + posterior iris epi

dilator + sphincter muscle

Question 11

bergmeister papilla

Answer 11

glial tissue persists at ONH

• posterior remnant on lens
• remnants of the fetal hyaloid system
• posterior remnant of the hyaloid system

Question 12

what structure is the retina formed from?

Answer 12

optic cup

Question 13

Mittendorf dot

Answer 13

small, circular opacity on the posterior lens capsule, classically nasal in location, which represents the anterior attachment of the hyaloid artery

Question 14

what is the GCL + INL like at birth?

Answer 14

still thin layer across fovea

Question 15

when are the GCL + INL completely displaced from fovea

Answer 15

4 months post birth

Question 16

what is corneal curvature

Answer 16

• circular + steep (55D) @ birth

- decreases to 40D 6mo after birth

Question 17

what is the first step in corneal development and when does it happen

Answer 17

day 33- corneal epi from surface ectoderm

Question 18

aniridia

Answer 18

absence of iris- altered depth of focus

Question 19

iris: neural crest cells

Answer 19

iris stroma

Question 20

when does myelination reach the chiasm? lamina cribosa?

Answer 20

chiasm: 6 mo

Question 21

what is the horizontal raphe

Answer 21

wraps around mac bundles to get back to optic disc –> brain
-horizontal raphe is temporary

Question 22

when does myelination reach lamina cribosa?

Answer 22

LC: 1-3 mo after birth

-visual implications, foveal displacement, cone development, myelination

Question 23

where does myelination travel from and to

Answer 23

from brain –> eye

LGN –> lamina cribosa

Question 24

horizontal raphe fibers

Answer 24

inferior and superior fibers dont cross

if damage to NFL - VD respects midline

Question 25

inferior damage in horizontal raphe

Answer 25

superior VFD

Question 26

where does maturation of PR occur

Answer 26

fovea + macula

Question 27

what is in hollow eye ball

Answer 27

empty space filled w/ CSF | continuous w/ 3rd V

Question 28

mesenchyme iris

Answer 28

anterior border layer

Question 29

how long can iris darken

Answer 29

6 mo after birth | bc --> blood to cornea

Question 30

hyaloid artery system process

Answer 30

hyaloid artery (ICA branch) enters optic cup through fetal fissure, filling the vitreous cavity, supplies nutrients to lens

Question 31

neural plate- what happens at week 3

Answer 31

thickening of ectoderm on the dorsal side

Question 32

when do cones migrate towards center

Answer 32

4-5 yrs after birth | 20/20 at age 5

Question 33

what does neural plate gives rise to

Answer 33

CNS + ocular structures

Question 34

what gives rise to hyaloid artery system

Answer 34

mesenchyme ( CT of globe)- neural crest and/or mesoderm

Question 35

hyaloid artery system: 4th month

Answer 35

atrophy- totally reabsorbed by birth- to supply to nutrients to lens

Question 36

eyelids: surface ectoderm

Answer 36

- skin + conj epi - hair follicles + cilia - meibomian glands - zeis glands - glands of moll

Question 37

when/where does CRA develop from?

Answer 37

month 4 from HAR

Question 38

when does CRA fully develop?

Answer 38

3mo after birth

Question 39

what happens to RPE in week 3-4

Answer 39

RPE pigmentation seen in outer later of optic cup

Question 40

when does optic pit form into the optic cup

Answer 40

day 25

Question 41

neural crest cells do what

Answer 41

tissue that differentiates

Question 42

what are optic pits

Answer 42

indentations form on the surface of the neural tube

Question 43

when do INL and GCL begin to move to peripheral macula

Answer 43

month 7

Question 44

when does pupillary membrane form between lens + cornea and why

Answer 44

month 3

Question 45

when does pupillary membrane completely break off

Answer 45

month 8.5

Question 46

when do the optic pits form

Answer 46

day 22

Question 47

coloboma: key hole pupil

Answer 47

bilateral- light sensitive

Question 48

orbit: neural crest cells

Answer 48

orbit fat + CT

Question 49

when does neural retinal cells differentiate

Answer 49

month 3

Question 50

what is the potential space between the neural retina + RPE

Answer 50

site of retinal detachment | NR + retina separated

Question 51

what is micropthalmos

Answer 51

small globe; incomplete development of optic cup + lens (lack of induction) likely a blind eye

Question 52

when does the lens placode form and how

Answer 52

day 27 | induction: formation of some structures depends on interactions among other tissues

Question 53

what week is the embryonic plate formed by

Answer 53

week 3

Question 54

what does the lens vesicle form and how

Answer 54

day 33 | forms once it separates form surface ectoderm

Question 55

persistent pupillary membrane

Answer 55

remains attached to lens or free floating | very common 17-32%

Question 56

what is primary vitreous

Answer 56

degenerating tissue from hyaloid system + fibers ret + lens

Question 57

when does myelination begin and why

Answer 57

months 5 - when axons reach the LGN

Question 58

what is secondary vitreous

Answer 58

encloses primary vitreous forming cloquets canals | forms attachment at vitreous base + hyaloid capsular ligament

Question 59

when does the fetal fissure begin to fuse

Answer 59

week 5 (goes anteriorly --> posteriorly)

Question 60

when does fetal fissure close

Answer 60

week 7

Question 61

what gives rise to the lens capsule

Answer 61

BM

Question 62

what type of cell gives rise to sclera

Answer 62

neural crest cells | goes around optic cup until reaches ON

Question 63

retina coloboma

Answer 63

no RPE can see straight through sclera unilateral can have no light perception

Question 64

continuous | outer --> ? --> CB --> inner

Answer 64

anterior epithelium w/ dilator + sphincter muscle --> CB --> posterior epi

Question 65

continuous | outer --> ? --> IRIS --> inner

Answer 65

anterior pigmented epi --> CB --> inner non-pig epi

Question 66

continuous | outer --> ? --> RETINA --> inner

Answer 66

RPE --> retina --> neural retina

Question 67

how is the optic stalk made

Answer 67

tissue joining the vesicle to the neural tube constricts

Question 68

what structures are needed for the lens placode to develop

Answer 68

optic vesicle and surface ectoderm

Question 69

y suture cataract

Answer 69

allows lines of suture, very common can see around- not visually important can use location for timeline of development

Question 70

retinopathy of prematurity

Answer 70

baby born early- put in 02 chamber retinal bv dont develop bc no need after taken out - you get neovascularization- ret detach now they gradually take out to complete growth

Question 71

what happens in neural retina at week 7

Answer 71

migration of the proliferative zone rpe --> outer neuroblastic layer (2 cells) --> transient later chievits --> inner neuroblastic layer (2 cells) --> marginal zone of His --> vitreous

Question 72

eyelids mesenchyme

Answer 72

tarsal plate, obicularis, tarsal plate muller - rare for muscles to be formed by neural cells - sphincter + dilator is an exception

Question 73

day 22- neural

Answer 73

neural folds fuse to form neural tube --> brain + spinal cord brain = neural ectoderm

Question 74

ocular albinism

Answer 74

reduced pigmentation of ocular structure, no foveal depression, BVA: 20/30 -underdeveloped macula from lack of signals from RPE

Question 75

what 2 zones does the neural retina form

Answer 75

proliferative (germinative) zone: outer closest to RPE, has cell bodies ( 4 cells) marginal zone of His (inner, anuclear)

Question 76

CB: neural crest

Answer 76

ciliary muscle, ciliary stroma

Question 77

CB: neural ectoderm

Answer 77

outer pigment epi, inner non-pig epi

Question 78

what gives rise to choroid and what structures needed

Answer 78

neural crest cells | needs RPE contact or proper development

Question 79

when does hyaloid artery system begin

Answer 79

week 5

Question 80

neural crest cells: cornea

Answer 80

cornea stroma + endo

Question 81

when does development of neural retina

Answer 81

week 4-6 cells of inner layer of optic cup form 2 zones

Question 82

congenital cataract | embryonic cataract

Answer 82

formation in embryonic nucleus | devasting to vision, surgery to avoid amblyopia

Question 83

when do neural retinal cells differential

Answer 83

month 3

Question 84

when does the neural groove and neural folds form

Answer 84

day 18-21

Question 85

lacrimal gland development

Answer 85

not fully formed at birth | not developed until 3-4yo

Question 86

when/where first place to see pigment in body and when

Answer 86

RPE at week 3-4

Question 87

when does optic pit turn into optic cup

Answer 87

day 25

Question 88

optic stalk -->

Answer 88

optic nerve

Question 89

fetal nucleus

Answer 89

anterior: upright y posterior: inverted y cells go posteriorly + anteriorly until they come together at midline

Question 90

when does folds of surface ectoderm + mesenchyme grow together

Answer 90

month 2