Embryo Flashcards
<p>Arrange the following structures in order of formation of the eye:</p>
<ul> <li>optic pits</li> <li>optic cups</li> <li>embryonic plate</li> <li>optic vesicles</li> <li>neural plate</li></ul>
<p>embryonic plate--> neural plate--> optic pits-->optic vesicles --> optic cups</p>
<p>What are the 3 layers that make up the Embryonic Plate?</p>
<ol> <li>Ectoderm</li> <li>Mesoderm</li> <li>Endoderm</li></ol>
<p>Which layer of the embryonic plate forms the eye and brain? </p>
<p>Ectoderm </p>
<p>What are the 3 layers that make up ectoderm?</p>
<ul> <li>Neural ectoderm</li> <li>Surface ectoderm</li> <li>Neural crest</li></ul>
<p>Whatis the blue layer on the figure?</p>
<p>Ectoderm</p>
<p>What is the yellow layer on the figure?</p>
<p>Mesoderm</p>
<p>What is the red layer on the figure?</p>
<p>Ectoderm</p>
<p>What is the central green structure prior to folding of the embryonic plate?</p>
<p>Notochord</p>
<p>What is the analogous structure to the notochord after folding?</p>
<p>Neural Tube</p>
<p>What is the name of the layer of ectoderm indicated?</p>
<p>Neural Plate</p>
<p>Which ectodermal cells migraine into the pockets shown?</p>
<p>Neural crest cells</p>
<p>What does the endoderm fold to form?</p>
<p>Gastrointestinal Tube</p>
<p>The optic pit forms at which day of gestation?</p>
<p>Day 23</p>
<p>What is the optic vesicle?</p>
<p>anterolateral outpouching of primitive brain stem</p>
<p>When does the optic vesicle form the globe?</p>
<p>evaginates on day 25 and becomes the globe</p>
<p>On which day does the optic vesicle induce the lens placode?</p>
<p>Day 25</p>
<p>Name some of the possible disordersthat can arise from abnormalities in envagination of the optic vescile.</p>
<ul> <li>anophthalmia</li> <li>cyclopia (synophthalmia)</li> <li>congenital cystic eye</li> <li>congenital nonattachment of the retina</li></ul>
<p>Name 4 disorders that are associated with synopthalmia</p>
<p>Apical forebrain lesions such as synophthalmia are associated with arrhinencephaly, proboscis, ethmocephaly, trisomy 13</p>
<p>How does the optic cup develop?</p>
<p>develops embryologically as an anterolateral evagination of the forebrain</p>
<p>What does the inner layer of the optic cup become?</p>
<p>Inner layer becomes the retina</p>
<p>What does the outer layer of the optic cup become?Outer layer becomes the retinal pigment epithelium</p>
<p>Outer layer becomes the retinal pigment epithelium</p>
<p>What does the potential space between the inner and outer layer of the optic cup become?</p>
<p>Potential space between the two becomes the SUBRETINAL SPACE (which was the cavity of the neural tube)</p>
<p>What do cells at the anterior margin of the optic cup form?</p>
<p>the posterior pigment epithelium of the iris</p>
<p>As the optic cup forms, what do cells between the future iris and the future retina form?</p>
<p>the ciliary body</p>
<p>What does the lens pit form before it bcomes the Lens vesicle?</p>
<p>Lens pore</p>
<p>where is the embryonic fissure located on the optic cup?</p>
<p>undersurface</p>
<p>When does the embyonic fissure close?</p>
<p>closes on day 33 allowing pressurization of globe</p>
<p>Where does the closure of the embryonic fissure begin?</p>
<p>Closure occurs first in midzone/equator, then extends posteriorly and anteriorly</p>
<p>what embronic tissue uses the embyonic fissure as a portal to enter the eye?</p>
<p>Embronic fissure serves as portal for mesoderm to enter eye (i.e. hyaloid artery)</p>
<p>What is it called when the embyonic fissure fails to close?</p>
<p>Coloboma</p>
<p>What is the inheritance pattern of colobomas?</p>
<p>sporadic or autosomal dominant (AD)</p>
<p>What is the typical quadrant location of a coloboma?</p>
<p>typical (located in inferonasal quadrant)</p>
<p>If a coloboma involves the retina and choroid what other conditions or syndromes can it be associated with?</p>
<p>associated with basal encephalocele, cleft palate, and CHARGE syndrome)</p>
<p>Is eyelid coloboma associated with closure of the embryonic fissure?</p>
<p>No</p>
<p>What do you call a small, abnormal eye with cystic expansion extending postioerly into theorbit?</p>
<p>Microphthalmos with cyst</p>
<p>Where does the cyst in microphthalmos with cyst typically arise?</p>
<p>Arises in area of and external to a choroidal coloboma</p>
<p>What kind of tissues are contained in the cyst with microphthalmos with cyst?</p>
<p>cyst usually contains dysplastic neuroectodermal tissue and may not directly connect with the eye</p>
<p>T/F: an optic pit is a coloboma?</p>
<p>True, an optic pit is considered an atypical coloboma</p>
<p>What abnormality is associated with optic pit?</p>
<p>basal encepholocele</p>
<p>Through wich structure does the hyaloid artery enter the eye?</p>
<p>embryonic fissure</p>
<p>What stucture does the hyaloid artery form?</p>
<p>vasa hyaloidea propria</p>
<p>what does thevasa hyaloidea propria supply blood to?</p>
<p>primary vitreous</p>
<p>At what gestational age does the intravitreal portion of the hyaloid artery regress?</p>
<p>8.5 months</p>
<p>What does the intraneural portion of the hyaloid artery form?</p>
<p>central retinal artery</p>
<p>What supplies blood flow to the posterior lens in embryologic development?</p>
<p>Posterior tunica vasculosa</p>
<p>At what gestational age does retinal vscular devlopement begin?</p>
<p>16th week</p>
<p>what cell type located next to the hyaloid artery formcapillary network, then form arteries and veins</p>
<p>mesenchymal cells</p>
<p>in what pattern do retinal vessels grow?</p>
<p>vessels grow centrifugally from optic disc</p>
<p>When do retinal blood vessels reach the ora serrata?</p>
<p>Nasal: 8 months</p>
<p>Temporal: 1-2 months later</p>
<p>what percentageof normal neonates have a patent hyaloid artery?</p>
<p>3%</p>
<p>Name the 4 remnants of hyaloid vasculature system</p>
<ol> <li>Bergmeister Papillae</li> <li>Peripapillary Loop</li> <li>Mittendorf's Dot</li> <li>Peristent Pupillary membrane</li></ol>
<p>Where is a Bergmeister papillae located?</p>
<p>At the optic nerve head</p>
<p>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</p>
<p>glial sheath of Bergmeister envelops posterior third of hyaloid artery and begins to atrophy during 7th month</p>
<p>What is seen if the glial sheath of the bergmeister papillae does not fully regress?</p>
<p>epipapillaryveil</p>
<p>From what structure does the peipapillar loop extend?</p>
<p>optic nerve head</p>
<p>What ocular conditions is one at increased risk for if a Peripapillary loop is present?</p>
<p>risk of artery obstruction or vitreous hemorrhage</p>
<p>Where is a mittendorf's dot located?</p>
<p>at the posterior lens capsule</p>
<p>what does the mittendorf's dot represent?</p>
<p>location where thehyaloid artery is attached to posterior tunica vasculosa lentis</p>
<p>what does a persistent pupillary membrane represent?</p>
<p>remnants of anterior tunica vasculosa lentis</p>
<p>Which cells eventually form the optic disc?</p>
<p>Primative epithelial papillae-cells from inner layer of optic cup at superior end of embryonic fissure</p>
<p>Axons of which cell type grow through the primartive epithelial papillae?</p>
<p>ganglion cells</p>
<p>Does myelination of the optic nerve start centrally or peripherally?</p>
<p>centrally</p>
<p>At what gestational age does myelination of the optic nerve reach the chiasm?</p>
<p>7.5 months</p>
<p>At what gestational age does myelination of the optic nerve reach the lamina cribrosa?</p>
<p>birth</p>
<p>At what gestational age ismyelination of the optic nerve complete?</p>
<p>approximately 1 month after birth</p>
<p>What is the embronic structure that is contiguous with the retinal ILM that covers the optic nerve?</p>
<p>Inner limiting membrane of Elschnig</p>
<p>Why can newborns optic nerves appear exaggeratedly cupped initially?</p>
<p>ON may show deceptively exaggerated cupping because nerve fibers posterior to lamina cribrosa are incompletely myelinated at birth</p>
<p>What systemic condition is associated with optic nerve hypoplasia?</p>
<p>DeMorsier's Syndrome</p>
<p>What percentage of patient's with DeMorsier's Syndrome have pituitary abnormalities?</p>
<p>13%</p>
<p>Which 3 ocular strutures produce the vitreous?</p>
<ol> <li>lens</li> <li>retina</li> <li>walls of the hyaloid artery</li></ol>
<p>What type of embyonic cells are contained in the vitreous?</p>
<p>mysechymal cells</p>
<p>What forms the primary vitreous?</p>
<p>hyaloid vascular system</p>
<p>whatblood vessels systemmake up the hylaloid vascular system (aka vasa hyaloidea propria)?</p>
<p>hyaloid canal</p>
<p>hyaloid vessels</p>
<p>posterior portions of tunica vasculosa lentis</p>
<p>What eventually replaces the primary vitreous?</p>
<p>secondary vitreous</p>
<p>What is the disease state caused by failure of the primary vitreous to regress?</p>
<p>persistent hyperplastic primary vitreous (PHPV)</p>
<p>By which ocular structureis the secondarty vitreous formed?</p>
<p>the retina</p>
<p>What is the name of the area that extends from the disc into the vitreous?</p>
<p>Area of Martegiani</p>
<p>What does theArea of Martegiani become?</p>
<p>Cloquet's canal</p>
<p>What is does Cloquet's canal represent?</p>
<p>junction of primary and secondary vitreous</p>
<p>What ocular strutures important to cataract surgery make up the tertiary vitreous?</p>
<p>zonule fibers</p>
<p>Which ocular structures from the tertiary vitreous?</p>
<p>ciliary processes and lens capsule</p>
<p>Name the embryologic space directly behind the lens</p>
<p>Berger's space</p>
<p>Of which embryologic tissue is teh retina derived?</p>
<p>neuroectoderm</p>
<p>When does retinal vascularization begin?</p>
<p>4 months</p>
<p>Which area of the retina is the last to become vascularized?</p>
<p>termporal periphery</p>
<p>At what age is development of the fovea complete?</p>
<p>4 weeks after birth</p>
<p>What is the condition called in which there is anabnormal proliferation of developing retina produces tubular structures with a rosette-like appearance?</p>
<p>Retinal dysplasia</p>
<p>How does retinal dysplasia occur?</p>
<p>It is anonspecific response to disorganizing influence during development</p>
<p>There are 8 conditions associated with retinal dysplasia, name at least 4 of them</p>
<ol> <li>materal LSD use</li> <li>Patau syndrome (trisomy 13)</li> <li>microphthalmos</li> <li>congenital gluacoma</li> <li>Peter's anomaly</li> <li>uveal and optic nerve colobomas</li> <li>cycloplia</li> <li>synophthalmia</li></ol>
<p>From which embryologic tissue is the stromal choroid derived?</p>
<p>neural crest cells</p>
<p>From which embrologic tissue is the vascular endothelium derived?</p>
<p>mesoderm</p>
<p>From which embryologic tissue are choroidal blood vessel walls derived?</p>
<p>neural crest cells</p>
<p>From which embryologic tissues is the scelra derived?</p>
<p>nerual crest cells</p>
<p>mesoderm (temporal aspect)</p>
<p>Why do babies have a blueish hue to their sclera at birth?</p>
<p>due to thinness (seeing the underlying uveal pigment)</p>
<p>From which embryologic tissue is the cornea derived?</p>
<p>neural crest cells (2 waves)</p>
<p>Between which 2 ocular tissues does the first wave of neural crest cell migration occur to form a duble layer of corneal endothelium?</p>
<p>epithelium and the lens</p>
<p>Between which two ocular tissuesdoes the 2nd wave of neural crest migration occur?</p>
<p>epithelium and endothelium</p>
<p>The second wave of neural crest cell migration in conreal formation is rich in which biochemicals?</p>
<p>hyaluonic acid and collagen fibrils</p>
<p>Atwhich gestational age does Descemet's membrane develop?</p>
<p>4 months</p>
<p>Atwhich gestational age does Bowman'smembrane develop?</p>
<p>5 months</p>
<p>From which embryologic tissue is the angle derived?</p>
<p>neural crest cells from peripheral cornea differentiate into chamber angle</p>
<p>At which gestational age does the angle develop?</p>
<p>7th week</p>
<p>Atwhich gestational age does Schlemm's canal develop?</p>
<p>4th month</p>
<p>Atwhich gestational age does the angle move posteriorly?</p>
<p>7th month</p>
<p>Atwhich gestational is the formation of the angle complete?</p>
<p>8th month</p>
<p>Atwhich gestational agedoes the trabecular meshwork appear?</p>
<p>just before birth</p>
<p>Atwhich gestational age does the lens begin to form?</p>
<p>27 days</p>
<p>What tissues begin to form the lens?</p>
<p>surface ectoderm adjacent to optic vesicle enlarges to form lens placode</p>
<p>Describe the steps involved in the development of the lens outlined in the drawing:</p>
<ol> <li>Circular indentationoccurs on lens plate, forming lens pit, which invaginates the wall of the optic vesicle until it closes to form a sphere</li> <li>Basement membrane of the surface ectoderm forms the surface of the sphere (the lens vesicle) and subsequently becomes the lens capsule</li> <li>Lens epithelial cells on posterior aspect of this sphere elongate and migrate first (primary lens fibers)</li> <li>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</li></ol>
<p>At what gestational age do the posterior lens epithelialcells fill the core of the lens to form the embryonal nucleus?</p>
<p>40 days</p>
<p>What do the Y sutures represent?</p>
<p>the meeting of embryonal and fetal nuclei</p>
<p>Describe the orientation of the "Y" of the Y suture in the anterior lens and posterior lens</p>
<p>upright anteriorly, inverted posteriorly</p>
<p>At which gestational age does the lens placode form?</p>
<p>3 weeks</p>
<p>From which embryologic tissue does the lens placode form?</p>
<p>surface ectoderm</p>
<p>At which gestational age does the lens vesicle form?</p>
<p>6 weeks</p>
<p>Further development of the lens vesicle requires which ocular tissue to be normal to proceed?</p>
<p>Normal neuroretina</p>
<p>At which gestational age does the tunica vasculosa lentisform?</p>
<p>12 weeks</p>
<p>At which gestational age does the tunica vasculosa lentis degenerate?</p>
<p>28-38 weeks</p>
<p>Why would the anterior chamber of a newborn appear more shallow than an adult?</p>
<p>Lens of a newborn is more spherical than that of an adult</p>
<p>How does the iris form?</p>
<p>rim of optic cup grows around lens and forms iris</p>
<p>From which embryologic strucutre does the Iris pigment epithelium develop?</p>
<p>from inner and outer layers of the optic cup</p>
<p>Describe the pigmentation status of the anterior and posterior iris pigment epitheliumanterior pigmented and posterior nonpigmented</p>
<p>anterior pigmented and posterior nonpigmented</p>
<p>From which embryologic tissue dothe IPE layers develop?</p>
<p>neuroectoderm</p>
<p>Iris pigment epithelium forms which important ocular divide?</p>
<p>blood-aqueous barrier</p>
<p>At which gestational age does the iris stroma form from neural crest cells?</p>
<p>7th week</p>
<p>At which gestational age does the sphincter and dilator muscles form?</p>
<p>7th week</p>
<p>From which embryologic tissues are thesphincter and dilator muscles derived?</p>
<p>neuroectoderm</p>
<p>At which gestational age blood vessels enter the iris?</p>
<p>7th month</p>
<p>At which gestational age does the tunica vaculosa lentis disappear?</p>
<p>9th month</p>
<p>What color is the typical pigmentation of the newborn iris?</p>
<p>grey-blue</p>
<p>How does the final color of the iris develop?</p>
<p>stromal chromatophores (dendritic melanocytes from neural crest) complete their migration into uvea shortly after birth</p>
<p>Why do newborns have relative miosis in infancy?</p>
<p>Iris dilator muscle is immature</p>
<p>which two tissues form the outer layer of the optic cup?</p>
<p>RPE and posterior iris pigment epithelium</p>
<p>why does the outer layer of the optic cup have matuer pigmentation?</p>
<p>pigment granules develop very early in gestation</p>
<p>when does the formation of the ciliary body begin?</p>
<p>3rd month</p>
<p>what becomes the epithelial layers of the ciliary processes?</p>
<p>folds in the optic cup</p>
<p>At which gestational age do ciliary bodyfilaments from surface cells form zonules; the major arterial circle of the iris (located in CB), the longitudinal ciliary muscle, and the ciliary processes develop?</p>
<p>4th month</p>
<p>At which gestational age does the pars plana, ciliary body stroma and ciliary muscle develop?</p>
<p>5th month</p>
<p>From whcih embryologic tissues does the paras plana, ciliary muscle and ciliary body stromadevelop?</p>
<p>neural crest cells adjacent to cornea</p>
<p>At which gestational age do the circular fibers of the ciliary muscle differentiate?</p>
<p>7th month</p>
<p>How can you tell how old a person is by looking at their ciliary body?</p>
<p>Patient’s age can be determined by analysis of CB cellularity</p>
<p>At which gestational age does the nasolacrimal system begin to develop?</p>
<p>6 weeks</p>
<p>What is the first sign of the formation of the nasolacrimal system?surface ectoderm is buried in mesoderm, between maxillary and lateral nasal processes</p>
<p>surface ectoderm getsburied in mesoderm, between maxillary and lateral nasal processes</p>
<p>At whatgestational age does the nasaolacrimal system canalize?</p>
<p>3rd month</p>
<p>What defects can result from problems in canalization of the nasolacrimal system?</p>
<p>may result in imperforate valve of Hasner; rarely, absent puncta or canaliculi</p>
<p>At what gestational age does the eyelids begin to form?</p>
<p>8 weeks</p>
<p>The fusion of whichtissues form the upper eyelids?</p>
<p>medial and lateral frontonasal processes</p>
<p>The fusion of whichtissues form the lowereyelids?</p>
<p>maxillary processes and medial nasal processes</p>
<p>At what gestational age do eyelid folds fuse?</p>
<p>12 weeks</p>
<p>At what gestational age do eyelids begin to seperate?</p>
<p>24 weeks</p>
<p>do eyelids begin to seperate from the nasal or lateral side?</p>
<p>nasal</p>
<p>From which embryologic tissue does the sensory retina develop?</p>
<p>Neural ectoderm</p>
<p>From which embryologic tissue does the RPE develop?</p>
<p>Neural ectoderm</p>
<p>From which embryologic tissue does nonpigmented ciliary body epithelium develop?</p>
<p>Neural ectoderm</p>
<p>From which embryologic tissue does the the pigmented CB epitheliumdevelop?</p>
<p>Neural ectoderm</p>
<p>The pigmeneted CB epithelium is an extension of which tissue?</p>
<p>RPE</p>
<p>From which embryologic tissue does the IPE develop?</p>
<p>Neural ectoderm</p>
<p>From which embryologic tissue does the iris sphincter and dilator muscledevelop?</p>
<p>neural ectoderm</p>
<p>From which embryologic tissue does the optic nerve (glialand neural elements)develop?</p>
<p>Neural ectoderm</p>
<p>From which embryologic tissue does the sympathetic ganglion and lateral geniculare body develop?</p>
<p>neural ectoderm</p>
<p>From which embryologic tissue does ocular pigment granulesdevelop? (RPE, CB, IPE)</p>
<p>neural ectoderm</p>
<p>From which embryologic tissue do the peripheral nerves related to eye functiondevelop?</p>
<p>neural ectoderm</p>
<p>From which embryologic tissue dothe erector pili muscle associated with hair follicles of the skindevelop?</p>
<p>neural ectoderm</p>
<p>From which embryologic tissue does the crystalline lens develop?</p>
<p>Surface ectoderm</p>
<p>From which embryologic tissue does the corneal and conjunctival epitheliumdevelop?</p>
<p>surface ectoderm</p>
<p>From which embryologic tissue does the eyelid epithelium develop?</p>
<p>surface ectoderm</p>
<p>From which embryologic tissue does the lacrimal glanddevelop?</p>
<p>surface ectoderm</p>
<p>From which embryologic tissue does the nasolacrimal systemdevelop?</p>
<p>surface ectoderm</p>
<p>From which embryologic tissue does the vitreous develop?</p>
<p>surface and neural ectoderm</p>
<p>From which embryologic tissue dothe zonules develop?</p>
<p>surface and neural ectoderm</p>
<p>From which embryologic tissue does the corneral stroma and endotheliumdevelop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue does the iris stromadevelop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue does the trabecular meshwork develop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue doesSchlemm's canal develop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue does the sclera (except temporal portion)develop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue does the sheaths and tendons of extraocular musclesdevelop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue does the ciliary muscle (nonpigmented layer of the ciliary body)develop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue does the choroidal stromadevelop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue do melanocytesdevelop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue domeningeal sheaths develop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue dothe orbital bones develop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue does the connective tissue of the orbitdevelop?</p>
<p>neural crest cells</p>
<p>From which embryologic tissue dothe musclar and connective tissue layers of the blood vesselsdevelop?</p>
<p>neural crest cells</p>
<p>What stain is specific for neural crest derived structures?</p>
<p>S-100 stain</p>
<p>What what gestational age do the 3 waves of Neural crest cell migration occur?</p>
<p>7th week</p>
<p>Name 3 ocular structures that are forme dby the waves of neural crest cell migration</p>
<ol> <li>corneal and TM endothelium</li> <li>keratocytes (corneal stroma)</li> <li>iris stroma</li></ol>
<p>Name the 5 conditions that can be caused by abnormal neural crest migration.</p>
<ol> <li>congenital glaucoma</li> <li>posterior embryotoxin</li> <li>Axenfield-Reiger syndrome</li> <li>Peter's anomaly</li> <li>sclerocornea</li></ol>
<p>Which ocular syndromes result from an abnormal proliferation of neural crest cells?</p>
<p>iridocorneal endothelial (ICE)syndromes</p>
<p>Which ocular conditions result from an abnormal terminal induction of neural crest cells?</p>
<p>corneal endothelial dystrophies</p>
<p>From which embryologic tissue does the blood vessel endotheliumdevelop?</p>
<p>mesoderm</p>
<p>From which embryologic tissue does the anterior chamber angle outflow apparatusdevelop?</p>
<p>mesoderm</p>
<p>From which embryologic tissue does the small temporal area of the scleradevelop?</p>
<p>mesoderm</p>
<p>From which embryologic tissue does the primative connective tissue develop?</p>
<p>mesenchyme</p>
<p>From which embryologic tissues does mesenchyme originate?</p>
<p>neural crest cells and mesoderm</p>
