Ocular Embryology Flashcards

1
Q

After notochord formation

A

Head end of embryonic disk of either side primitive streak ridges begin to appear in the ectoderm induced by notochord; adjacent neuroectodermal cells elongate become columnar rise meet and fuse dorsally forming future brain and more cuadally rest of neural tube

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2
Q

Squamous surface ectoderm

A

Will overlay columnar cells of neural tube; this will ultimately cover entire embryo

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3
Q

Neural tube closure

A

First closes in hind brain area the closure progresses rostraly; lateral dilations of hind brain midbrain and forebrain forming simultaneously

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4
Q

Neural crest cell at notochord closure

A

As neural tube is closing population of ectodermal cells between neural and surface ectoderm delaminate and disassociate from their neighbors these are neural crest cells

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5
Q

Flexion of embryo

A

Forbrain grows so fast it starts to raise up and pushes future heart, prechordal plate and septum transversum ventrally and caudally flexing embryo and placing heart oral cavity ect in correct place

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6
Q

First sign of eyes

A

Toward end of head folding, small groves appear inside bulges on surface of prosencephalon or forebrain

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7
Q

Eye field

A

Special cells that form initial small groves inside forebrain arise from anterior neural plate called eye field

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8
Q

Eye plate separation

A

Must separate or Cyclopes will occur

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9
Q

Optic grooves

A

Aka sulci; eye fields separates into two and invaginates forming optic groove

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10
Q

Optic cups

A

Optic vesicle invaginates and becomes optic cup; inner part of optic cup will begin to thicken as cells there are diferentiating and elongating to form neurosensory retina

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11
Q

Optic vesicles

A

Optic grooves (now completely enclosed by closed neural tube) balloon to form optic vesicles

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12
Q

Lens placode formation

A

Neuroectoderm of optic vessel contacts surface ectoderm inducing this formation

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13
Q

Inducing lens formation

A

Will have a neural tube with two optic stalks and an optic vesicle on far end of each stalk in contact with surface ectoderm about to induce lens formation

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14
Q

Lens formation

A

Surface epithelium thickens and becomes columnar (lens placode) then almost immediately invaginates; simultaneously surface ectodermal cells in posterior lens are elongating and filling cavity of lens vesicle

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15
Q

What layer is lens derives from

A

Ectoderm

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16
Q

Lens vesicle

A

Ectodermally derived lense pinches off of surface ectoderm forming lens vesicle; once this is pinched off the lens epithelium is encapsulated by basement membrane/ basil lamina of its epithelial cells so immune system does not recognize cells in lens protein bc immune system forms later in development

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17
Q

RPE differentiation

A

Retinal pigment epithelium differentiation is induced by neural crest cells

18
Q

First ocular tissue to show significant differentiation

A

Primitive lens when posterior lens cells elongate to fill cavity of lens vesicle forming the primary lens fibers

19
Q

Secondary lens fibers

A

Anterior lens epithelial cells migrate to lens equator start to elongate and eventually form secondary lens fibers; can only grow to a certain length

20
Q

Sutures

A

When secondary lens fibers can no longer entirely surround growing lens nucleus then fibers tips meet interdigital earth precisely and form seams called sutures; become more complex y shape with age

21
Q

Lens fiber clarity

A

These are clear in part because after elongating lens fibers lose their nucleus and intracelluar organelles

22
Q

Embryonic optic fissure

A

Aka choroidal fissure; groove or fissure present on ventral floor of developing optic cup; it is path for developing hyaloid vessels inside eye to exit the eye

23
Q

hyaloid vessels

A

nourish the developing lens and retina (developing from mesenchyme surrounding the cup and within the fissure)

24
Q

failed closure of optic fissure

A

if fissure fails to close properly congenital coloboma or hole may be noted in iris or other ocular tissues

25
Q

tunica vasculosa lentis

A

hyaloid vasculature will surround developing lens forming this (vessel surrounding lens)

26
Q

hyaloid stem

A

surrounds developing lens and begins to produce vitreous (also has contributions from developing lens and retina) around 7-8 weeks of development

27
Q

can hyaloid remnants remain after birth

A

yes in some animals particularly ruminants

28
Q

anterior chamber

A

appears when corneal stroma and corneal endothelium start to form from an influx of neural crest cells

29
Q

lid buds

A

ectodermal lid buds filled with mesoderm are forming eyelids which will migrate over cornea and fuse at aprox 10 weeks

30
Q

epithelium on side of eyelid facing cornea

A

differentiates into conjunctiva

31
Q

anterior most rim of optic cup

A

later in eye development iris epithelium and cilliary body epithelium differentiation from anterior most rim of optic cup; rim area elongates and grows between lens and cornea

32
Q

iris sphincter and iris dilator muscles

A

differentiate from optic cup (an external layer of neuroectodermal epithelium)

33
Q

iris sphincter and iris dilator muscle types

A

mamals: smooth

birds and reptiles: striated

34
Q

neural crest mesenchymal cells

A

cells in the area of optic rim are induced to form iris stroma, ciliary body stroma, and cilliary body muscles

35
Q

stabilization of the lens

A

vessels that surround lens (tunica vasculosa lentil) and hyaloid artery regress fibrils develop that attach the lens capsule to cilliary body epithelium stabilizing the lens

36
Q

structures surrounding oropharyngeal area

A

single frontonasal prominences, paired pharyngeal arches #1; frnotonasal prominence gives rise to paired medial and lateral nasal processes surrounding developing nasal placodes

37
Q

nasal pit formation

A

nasal prominences grow forward while placodes stay in place and nasal pits result

38
Q

nasal pits future

A

nasal cavities in future

39
Q

bilateral pharyngeal arches #1

A

one of structures surrounding oropharyngeal area; these give rise to paired maxillary processes and mandibular prominences derived from neural crest cells

40
Q

frontonasal prominence

A

one of structures surrounding oropharyngeal area; this gives rise to paired medal and lateral nasal prominences derived from neural crest cells

41
Q

future nasolacrimal ducts

A

Arise from cleavage of epithelial cord trapped between lateral nasal and maxillary prominences eventually connects developing nasal passages and medial cantonal area of eyelids

42
Q

midface

A

this is almost all neural crest cells