Retinal Development Flashcards by Andrea Sandifer

Where do the neural folds and groove originate on

Embryonic disc

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What is formed when the neural folds and groove get zipped

The neural tube

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What makes up the inner tube of the embryo

The neural tube

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What makes up the outer tube of the embryo

Surface ectoderm

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That liters between the 2 tubes of the embryo

Mesenchyme

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What are the 2 evaginations that form off the cranial portion of the neural tube

Optic vesicles

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What are the optic vesicles made of

Neural ectoderm

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The optic vesicles will elongate and form the

Optic stalk

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When the optic vesicles encounters the surface ectoderm what happens

It will fold in (invaginate)

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What does invagination of the surface ectoderm form

Optic cup

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As the optic cup folds in on itself, the back of the cup comes into contact with the layer from the front of the cup. This creates what relationship

Apex to apex

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What is the space that forms between the inner and outer layers of the optic cup

Intraretinal space

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What s the most posterior layer of the optic cup (outer layer)

RPE

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What is the inner layer of the optic cup

Neural retina

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The anterior outer layer is what tissue

Pigmented ciliary epithelium

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The anterior inner layer Is what tissue

Nonpigemnted epithelium

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The most anterior outer layer is what tissue

Anterior iris epithelium

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What tissue is the most anterior inner layer

Posterior iris epithelium

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What is the first layer of the retina to differentiate

The RPE

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Cellular structures and melanosomes begin to appear in the outer layer of the optic cup, and pigmentation of the retinal epithelium occurs when

Week 3-4

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What happens to the RPE at week 6

The RPE is 1 cell layer thick

Cuboidal-columnar shape

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Between weeks 4-6 the cells of the inner layer of the optic cup do what

Proliferate and form 2 zones

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The neural retina subdivides into 2 areas in what week of development

4-6

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What is the outer layer of the neural retina

Proliferation zone

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What is the inner zone of the neural retina

Marginal zone

What is layer of the retina is formed at weeks 4-6 | What is its function

Basal lamina (will become the ILM) Separates the retina from the vitreous

At week 7, cell migration occurs and forms these

Inner and outer neuroblastic layers

What lies between the inner and outer neuroblastic layers

Transient fiber layer of Chievitz

Differentiation of the neural retinal cells begins where

In the central retina and proceeds to the periphery

Formation of the neuroblastic layers is complete by this month

3rd month

Inner neuroblastic layer development

1. Ganglion cells migrate and form a layer close to the basement membrane 2. Biomolecular agents guide atonal growth toward termination in the lateral geniculate nucleus 3. Muller cells develop at the same time. Bodies of the Muller and amacrine cells remain in the inner neuroblastic layer but move toward the sclera

Outer neuroblastic layer development

1. Bipolar cells migrate from outer neuroblastic layer and settle near the Muller and amacrine cells 2. Horizontal cells follow 3. Diner layer of Chievitz is gradually obliterates by this move of bipolar and horizontal cells 4. Photoreceptor cells reman in the outer neuroblastic layer

By week 23 the photoreceptors are aligned along the outer side of the inner layer of the optic cup and _______ appear between them

Adhering jxns

What do the adhering junctions form eventually

The ELM

What are the last cells of the neural retina to differentiate When does this occur

Photoreceptor cells 5th month

What photoreceptor differentiates first? Second?when?

1st: cones 2nd: rod (7th month)

The inner segment creates a protuberance that embeds in teh RPE and continues to grow and form what? When?

Cilium Week 24-25

Where do the horizontal, bipolar, amacrine, and Muller cells develop

Inner nuclear layer

What are the inner and outer plexiform layers filled with

Neuronal processes

The fiber s of the Muller cells appear and extend to the basal lamina, forming this

Primitive internal limiting membrane

What is the function of the Muller cells

Provide scaffolding for cell development and appears to be involved with guiding the direction of atonal fiber growth

What develops first cone pedicles or rod spherules?

Cone pedicles

Photoreceptor synapses with ________ cells are established before the outer segments are completed

Bipolar cells

What is well established by month 5

Ganglion cell layer

Because the retinal development is more advanced centrally than peripherally what happens to the ganglion cells

Ganglion axons from the periphery must take an arched route above and below the macular area to reach teh nerve ahead

What is teh line of deviation at the horizontal temporal meridian Called

Horizontal raphe

What occurs to the retinal cells in the 5th month

Reduction of retinal cells by apoptosis

What occurs to the retinal cells at month 6

No further mitosis | Retinal growth continues because of cell differentiation, growth, and maturation

When do the cones differentiate

6th month

Why is the fovea thicker

There is a dense accumulation;action of nuclei (up to 9 rows of ganglion cells)

What are the 3 stages of foveal development

1. Displacement of inner retinal component form depression 2. Migration of photoreceptors toward the center, increases cone packing 3. Maturation of photoreceptors

When do the ganglion cells and inner nuclear cells move to the periphery of the macula

7th

How many layers are there of the ganglion cells and inner nuclear layer at birth

At 4 months pb the ganglion and INL are displaced to sloping walls of the fovea, leaving what as the only neural cell bodes in the center of the depression

Cones of the outer nuclear layer

What is the foveola

Retinal area of sharpest VA

What is the last region to mature

Foveola

Before birth the rod-free area is large compared to adults but becomes narrower with migration of the cones centrally, increasing cone density

Foveola

What is the cone population in the foveola in 1 week old infant

What is the cone population in the 4-5 y.o of the foveola

The cone inner fibers elongate and adopt what orientation Why does this occur?

Oblique orientation So they can synapse with the cells of the INL

What continues to develop during the first few years of life

Outer segment | Inner fiber lengthens

What can newborns see

Changes in brightness Non-moving vs moving objects Follow moving objects

What is the VA of newborn

20/800-20/200

What is the VA of 2 mo old

20/150

What is the VA of a 4 mo old

20/60

What is the VA of 6 mo old

20/20

Look at slide 35

Development flow chart

The foveal depression continues to deepen until what age (as cells move toward the macular periphery)

15 months pb