Embryo Flashcards
(201 cards)
1
Q
Arrange the following structures in order of formation of the eye:
- optic pits
- optic cups
- embryonic plate
- optic vesicles
- neural plate
A
embryonic plate–> neural plate–> optic pits–> optic vesicles –> optic cups
2
Q
What are the 3 layers that make up the Embryonic Plate?
A
- Ectoderm
- Mesoderm
- Endoderm
3
Q
Which layer of the embryonic plate forms the eye and brain?
A
Ectoderm
4
Q
What are the 3 layers that make up ectoderm?
A
- Neural ectoderm
- Surface ectoderm
- Neural crest
5
Q
What is the blue layer on the figure?
A
Ectoderm
6
Q
What is the yellow layer on the figure?
A
Mesoderm
7
Q
What is the red layer on the figure?
A
Ectoderm
8
Q
What is the central green structure prior to folding of the embryonic plate?
A
Notochord
9
Q
What is the analogous structure to the notochord after folding?
A
Neural Tube
10
Q
What is the name of the layer of ectoderm indicated?
A
Neural Plate
11
Q
Which ectodermal cells migraine into the pockets shown?
A
Neural crest cells
12
Q
What does the endoderm fold to form?
A
Gastrointestinal Tube
13
Q
The optic pit forms at which day of gestation?
A
Day 23
14
Q
What is the optic vesicle?
A
anterolateral outpouching of primitive brain stem
15
Q
When does the optic vesicle form the globe?
A
evaginates on day 25 and becomes the globe
16
Q
On which day does the optic vesicle induce the lens placode?
A
Day 25
17
Q
Name some of the possible disorders that can arise from abnormalities in envagination of the optic vescile.
A
- anophthalmia
- cyclopia (synophthalmia)
- congenital cystic eye
- congenital nonattachment of the retina
18
Q
Name 4 disorders that are associated with synopthalmia
A
Apical forebrain lesions such as synophthalmia are associated with arrhinencephaly, proboscis, ethmocephaly, trisomy 13
19
Q
How does the optic cup develop?
A
develops embryologically as an anterolateral evagination of the forebrain
20
Q
What does the inner layer of the optic cup become?
A
Inner layer becomes the retina
21
Q
What does the outer layer of the optic cup become? Outer layer becomes the retinal pigment epithelium
A
Outer layer becomes the retinal pigment epithelium
22
Q
What does the potential space between the inner and outer layer of the optic cup become?
A
Potential space between the two becomes the SUBRETINAL SPACE (which was the cavity of the neural tube)
23
Q
What do cells at the anterior margin of the optic cup form?
A
the posterior pigment epithelium of the iris
24
Q
As the optic cup forms, what do cells between the future iris and the future retina form?
A
the ciliary body
25
Name the following structures:
26
What does the lens pit form before it bcomes the Lens vesicle?
Lens pore
27
Name the following components of the formation of the optic cup.
28
where is the embryonic fissure located on the optic cup?
undersurface
29
When does the embyonic fissure close?
closes on day 33 allowing pressurization of globe
30
Where does the closure of the embryonic fissure begin?
Closure occurs first in midzone/equator, then extends posteriorly and anteriorly
31
what embronic tissue uses the embyonic fissure as a portal to enter the eye?
Embronic fissure serves as portal for mesoderm to enter eye (i.e. hyaloid artery)
32
What is it called when the embyonic fissure fails to close?
Coloboma
33
What is the inheritance pattern of colobomas?
sporadic or autosomal dominant (AD)
34
What is the typical quadrant location of a coloboma?
typical (located in inferonasal quadrant)
35
If a coloboma involves the retina and choroid what other conditions or syndromes can it be associated with?
associated with basal encephalocele, cleft palate, and CHARGE syndrome)
36
Is eyelid coloboma associated with closure of the embryonic fissure?
No
37
What do you call a small, abnormal eye with cystic expansion extending postioerly into the orbit?
Microphthalmos with cyst
38
Where does the cyst in microphthalmos with cyst typically arise?
Arises in area of and external to a choroidal coloboma
39
What kind of tissues are contained in the cyst with microphthalmos with cyst?
cyst usually contains dysplastic neuroectodermal tissue and may not directly connect with the eye
40
T/F: an optic pit is a coloboma?
True, an optic pit is considered an atypical coloboma
41
What abnormality is associated with optic pit?
basal encepholocele
42
Through wich structure does the hyaloid artery enter the eye?
embryonic fissure
43
What stucture does the hyaloid artery form?
vasa hyaloidea propria
44
what does the vasa hyaloidea propria supply blood to?
primary vitreous
45
At what gestational age does the intravitreal portion of the hyaloid artery regress?
8.5 months
46
What does the intraneural portion of the hyaloid artery form?
central retinal artery
47
What supplies blood flow to the posterior lens in embryologic development?
Posterior tunica vasculosa
48
At what gestational age does retinal vscular devlopement begin?
16th week
49
what cell type located next to the hyaloid artery form capillary network, then form arteries and veins
mesenchymal cells
50
in what pattern do retinal vessels grow?
vessels grow centrifugally from optic disc
51
When do retinal blood vessels reach the ora serrata?
Nasal: 8 months
Temporal: 1-2 months later
52
what percentage of normal neonates have a patent hyaloid artery?
3%
53
Name the 4 remnants of hyaloid vasculature system
1. Bergmeister Papillae
2. Peripapillary Loop
3. Mittendorf's Dot
4. Peristent Pupillary membrane
54
Where is a Bergmeister papillae located?
At the optic nerve head
55
Describe how the bergmeister papillae interacts with the hyaloid artery-glial sheath of Bergmeister envelops posterior third of hyaloid artery and begins to atrophy during 7th month
glial sheath of Bergmeister envelops posterior third of hyaloid artery and begins to atrophy during 7th month
56
What is seen if the glial sheath of the bergmeister papillae does not fully regress?
epipapillary veil
57
From what structure does the peipapillar loop extend?
optic nerve head
58
What ocular conditions is one at increased risk for if a Peripapillary loop is present?
risk of artery obstruction or vitreous hemorrhage
59
Where is a mittendorf's dot located?
at the posterior lens capsule
60
what does the mittendorf's dot represent?
location where the hyaloid artery is attached to posterior tunica vasculosa lentis
61
what does a persistent pupillary membrane represent?
remnants of anterior tunica vasculosa lentis
62
Which cells eventually form the optic disc?
Primative epithelial papillae- cells from inner layer of optic cup at superior end of embryonic fissure
63
Axons of which cell type grow through the primartive epithelial papillae?
ganglion cells
64
Does myelination of the optic nerve start centrally or peripherally?
centrally
65
At what gestational age does myelination of the optic nerve reach the chiasm?
7.5 months
66
At what gestational age does myelination of the optic nerve reach the lamina cribrosa?
birth
67
At what gestational age is myelination of the optic nerve complete?
approximately 1 month after birth
68
What is the embronic structure that is contiguous with the retinal ILM that covers the optic nerve?
Inner limiting membrane of Elschnig
69
Why can newborns optic nerves appear exaggeratedly cupped initially?
ON may show deceptively exaggerated cupping because nerve fibers posterior to lamina cribrosa are incompletely myelinated at birth
70
What systemic condition is associated with optic nerve hypoplasia?
DeMorsier's Syndrome
71
What percentage of patient's with DeMorsier's Syndrome have pituitary abnormalities?
13%
72
Which 3 ocular strutures produce the vitreous?
1. lens
2. retina
3. walls of the hyaloid artery
73
What type of embyonic cells are contained in the vitreous?
mysechymal cells
74
What forms the primary vitreous?
hyaloid vascular system
75
what blood vessels system make up the hylaloid vascular system (aka vasa hyaloidea propria)?
hyaloid canal
hyaloid vessels
posterior portions of tunica vasculosa lentis
76
What eventually replaces the primary vitreous?
secondary vitreous
77
What is the disease state caused by failure of the primary vitreous to regress?
persistent hyperplastic primary vitreous (PHPV)
78
By which ocular structure is the secondarty vitreous formed?
the retina
79
What is the name of the area that extends from the disc into the vitreous?
Area of Martegiani
80
What does the Area of Martegiani become?
Cloquet's canal
81
What is does Cloquet's canal represent?
junction of primary and secondary vitreous
82
What ocular strutures important to cataract surgery make up the tertiary vitreous?
zonule fibers
83
Which ocular structures from the tertiary vitreous?
ciliary processes and lens capsule
84
Name the embryologic space directly behind the lens
Berger's space
85
Of which embryologic tissue is teh retina derived?
neuroectoderm
86
When does retinal vascularization begin?
4 months
87
Which area of the retina is the last to become vascularized?
termporal periphery
88
At what age is development of the fovea complete?
4 weeks after birth
89
What is the condition called in which there is an abnormal proliferation of developing retina produces tubular structures with a rosette-like appearance?
Retinal dysplasia
90
How does retinal dysplasia occur?
It is a nonspecific response to disorganizing influence during development
91
There are 8 conditions associated with retinal dysplasia, name at least 4 of them
1. materal LSD use
2. Patau syndrome (trisomy 13)
3. microphthalmos
4. congenital gluacoma
5. Peter's anomaly
6. uveal and optic nerve colobomas
7. cycloplia
8. synophthalmia
92
What ocular structure/cell type does the choroid require for development?
93
From which embryologic tissue is the stromal choroid derived?
neural crest cells
94
From which embrologic tissue is the vascular endothelium derived?
mesoderm
95
From which embryologic tissue are choroidal blood vessel walls derived?
neural crest cells
96
From which embryologic tissues is the scelra derived?
nerual crest cells
mesoderm (temporal aspect)
97
Why do babies have a blueish hue to their sclera at birth?
due to thinness (seeing the underlying uveal pigment)
98
From which embryologic tissue is the cornea derived?
neural crest cells (2 waves)
99
Between which 2 ocular tissues does the first wave of neural crest cell migration occur to form a duble layer of corneal endothelium?
epithelium and the lens
100
Between which two ocular tissues does the 2nd wave of neural crest migration occur?
epithelium and endothelium
101
The second wave of neural crest cell migration in conreal formation is rich in which biochemicals?
hyaluonic acid and collagen fibrils
102
At which gestational age does Descemet's membrane develop?
4 months
103
At which gestational age does Bowman's membrane develop?
5 months
104
From which embryologic tissue is the angle derived?
neural crest cells from peripheral cornea differentiate into chamber angle
105
At which gestational age does the angle develop?
7th week
106
At which gestational age does Schlemm's canal develop?
4th month
107
At which gestational age does the angle move posteriorly?
7th month
108
At which gestational is the formation of the angle complete?
8th month
109
At which gestational agedoes the trabecular meshwork appear?
just before birth
110
At which gestational age does the lens begin to form?
27 days
111
What tissues begin to form the lens?
surface ectoderm adjacent to optic vesicle enlarges to form lens placode
112
Describe the steps involved in the development of the lens outlined in the drawing:
1. Circular indentation occurs on lens plate, forming lens pit, which invaginates the wall of the optic vesicle until it closes to form a sphere
2. Basement membrane of the surface ectoderm forms the surface of the sphere (the lens vesicle) and subsequently becomes the lens capsule
3. Lens epithelial cells on posterior aspect of this sphere elongate and migrate first (primary lens fibers)
4. At 7 weeks, anterior cells migrate toward equator and proliferate to form secondary lens fibers that encase the embryonal nucleus and form the Y sutures
113
At what gestational age do the posterior lens epithelial cells fill the core of the lens to form the embryonal nucleus?
40 days
114
What do the Y sutures represent?
the meeting of embryonal and fetal nuclei
115
Describe the orientation of the "Y" of the Y suture in the anterior lens and posterior lens
upright anteriorly, inverted posteriorly
116
At which gestational age does the lens placode form?
3 weeks
117
From which embryologic tissue does the lens placode form?
surface ectoderm
118
At which gestational age does the lens vesicle form?
6 weeks
119
Further development of the lens vesicle requires which ocular tissue to be normal to proceed?
Normal neuroretina
120
At which gestational age does the tunica vasculosa lentis form?
12 weeks
121
At which gestational age does the tunica vasculosa lentis degenerate?
28-38 weeks
122
Why would the anterior chamber of a newborn appear more shallow than an adult?
Lens of a newborn is more spherical than that of an adult
123
How does the iris form?
rim of optic cup grows around lens and forms iris
124
From which embryologic strucutre does the Iris pigment epithelium develop?
from inner and outer layers of the optic cup
125
Describe the pigmentation status of the anterior and posterior iris pigment epitheliumanterior pigmented and posterior nonpigmented
anterior pigmented and posterior nonpigmented
126
From which embryologic tissue do the IPE layers develop?
neuroectoderm
127
Iris pigment epithelium forms which important ocular divide?
blood-aqueous barrier
128
At which gestational age does the iris stroma form from neural crest cells?
7th week
129
At which gestational age does the sphincter and dilator muscles form?
7th week
130
From which embryologic tissues are the sphincter and dilator muscles derived?
neuroectoderm
131
At which gestational age blood vessels enter the iris?
7th month
132
At which gestational age does the tunica vaculosa lentis disappear?
9th month
133
What color is the typical pigmentation of the newborn iris?
grey-blue
134
How does the final color of the iris develop?
stromal chromatophores (dendritic melanocytes from neural crest) complete their migration into uvea shortly after birth
135
Why do newborns have relative miosis in infancy?
Iris dilator muscle is immature
136
which two tissues form the outer layer of the optic cup?
RPE and posterior iris pigment epithelium
137
why does the outer layer of the optic cup have matuer pigmentation?
pigment granules develop very early in gestation
138
when does the formation of the ciliary body begin?
3rd month
139
what becomes the epithelial layers of the ciliary processes?
folds in the optic cup
140
At which gestational age do ciliary body filaments from surface cells form zonules; the major arterial circle of the iris (located in CB), the longitudinal ciliary muscle, and the ciliary processes develop?
4th month
141
At which gestational age does the pars plana, ciliary body stroma and ciliary muscle develop?
5th month
142
From whcih embryologic tissues does the paras plana, ciliary muscle and ciliary body stroma develop?
neural crest cells adjacent to cornea
143
144
At which gestational age do the circular fibers of the ciliary muscle differentiate?
7th month
145
How can you tell how old a person is by looking at their ciliary body?
Patient’s age can be determined by analysis of CB cellularity
146
At which gestational age does the nasolacrimal system begin to develop?
6 weeks
147
What is the first sign of the formation of the nasolacrimal system?surface ectoderm is buried in mesoderm, between maxillary and lateral nasal processes
surface ectoderm gets buried in mesoderm, between maxillary and lateral nasal processes
148
At what gestational age does the nasaolacrimal system canalize?
3rd month
149
What defects can result from problems in canalization of the nasolacrimal system?
may result in imperforate valve of Hasner; rarely, absent puncta or canaliculi
150
At what gestational age does the eyelids begin to form?
8 weeks
151
The fusion of which tissues form the upper eyelids?
medial and lateral frontonasal processes
152
The fusion of which tissues form the lower eyelids?
maxillary processes and medial nasal processes
153
At what gestational age do eyelid folds fuse?
12 weeks
154
At what gestational age do eyelids begin to seperate?
24 weeks
155
do eyelids begin to seperate from the nasal or lateral side?
nasal
156
From which embryologic tissue does the sensory retina develop?
Neural ectoderm
157
From which embryologic tissue does the RPE develop?
Neural ectoderm
158
From which embryologic tissue does nonpigmented ciliary body epithelium develop?
Neural ectoderm
159
From which embryologic tissue does the the pigmented CB epithelium develop?
Neural ectoderm
160
The pigmeneted CB epithelium is an extension of which tissue?
RPE
161
From which embryologic tissue does the IPE develop?
Neural ectoderm
162
From which embryologic tissue does the iris sphincter and dilator muscle develop?
neural ectoderm
163
From which embryologic tissue does the optic nerve (glial and neural elements) develop?
Neural ectoderm
164
From which embryologic tissue does the sympathetic ganglion and lateral geniculare body develop?
neural ectoderm
165
From which embryologic tissue does ocular pigment granules develop? (RPE, CB, IPE)
neural ectoderm
166
From which embryologic tissue do the peripheral nerves related to eye function develop?
neural ectoderm
167
From which embryologic tissue do the erector pili muscle associated with hair follicles of the skin develop?
neural ectoderm
168
From which embryologic tissue does the crystalline lens develop?
Surface ectoderm
169
From which embryologic tissue does the corneal and conjunctival epithelium develop?
surface ectoderm
170
From which embryologic tissue does the eyelid epithelium develop?
surface ectoderm
171
From which embryologic tissue does the lacrimal gland develop?
surface ectoderm
172
From which embryologic tissue does the nasolacrimal system develop?
surface ectoderm
173
From which embryologic tissue does the vitreous develop?
surface and neural ectoderm
174
From which embryologic tissue do the zonules develop?
surface and neural ectoderm
175
From which embryologic tissue does the corneral stroma and endothelium develop?
neural crest cells
176
From which embryologic tissue does the iris stroma develop?
neural crest cells
177
178
From which embryologic tissue does the trabecular meshwork develop?
neural crest cells
179
From which embryologic tissue does Schlemm's canal develop?
neural crest cells
180
From which embryologic tissue does the sclera (except temporal portion) develop?
neural crest cells
181
From which embryologic tissue does the sheaths and tendons of extraocular muscles develop?
neural crest cells
182
From which embryologic tissue does the ciliary muscle (nonpigmented layer of the ciliary body) develop?
neural crest cells
183
From which embryologic tissue does the choroidal stroma develop?
neural crest cells
184
From which embryologic tissue do melanocytes develop?
neural crest cells
185
From which embryologic tissue domeningeal sheaths develop?
neural crest cells
186
From which embryologic tissue dothe orbital bones develop?
neural crest cells
187
From which embryologic tissue does the connective tissue of the orbit develop?
neural crest cells
188
From which embryologic tissue do the musclar and connective tissue layers of the blood vessels develop?
neural crest cells
189
What stain is specific for neural crest derived structures?
S-100 stain
190
What what gestational age do the 3 waves of Neural crest cell migration occur?
7th week
191
Name 3 ocular structures that are forme dby the waves of neural crest cell migration
1. corneal and TM endothelium
2. keratocytes (corneal stroma)
3. iris stroma
192
Name the 5 conditions that can be caused by abnormal neural crest migration.
1. congenital glaucoma
2. posterior embryotoxin
3. Axenfield-Reiger syndrome
4. Peter's anomaly
5. sclerocornea
193
Which ocular syndromes result from an abnormal proliferation of neural crest cells?
iridocorneal endothelial (ICE) syndromes
194
Which ocular conditions result from an abnormal terminal induction of neural crest cells?
corneal endothelial dystrophies
195
From which embryologic tissue does the blood vessel endothelium develop?
mesoderm
196
From which embryologic tissue does the anterior chamber angle outflow apparatus develop?
mesoderm
197
From which embryologic tissue does the small temporal area of the sclera develop?
mesoderm
198
From which embryologic tissue do the extraocular muscles develop?
199
From which embryologic tissue does the primative connective tissue develop?
mesenchyme
200
From which embryologic tissues does mesenchyme originate?
neural crest cells and mesoderm
201
Reference of timeline for Ocular Development:
