A&P Eye Ocular Development

growth

Change in size of a cell, tissue, or organism

stem cells

cells that are non-differentiated; either early in neurogenesis or within specific structures capable of continuous growth

cell determination

A cell commits to a certain developmental pathway

induction

One tissue affecting the growth and development of another

cascading induction

Chain effect; numerous induction events depend on an initial primary inducer; break in chain will affect development of structures further down the chain; earlier the issue-→greater effect

differentiation

Change to a more specific structure or function on a cellular level

migration

movement of cells in organized waves toward a target location

embryonic period

Early state where cell lines are germinated and organs develop

1. Germinal period
2. Organogenesis period

What are the 2 divisions of the embryonic period?

germinal period

Which division of the embryonic period is characterized through the development of germinal layers?

organogenesis period

Which division of the embryonic period is characterized through the development of primitive organs?

3-9 months

In what months during development is the fetal period?

1. Ectoderm
2. Mesoderm
3. Endoderm

What are the 3 primary germ layers?

Ectoderm & mesoderm

Which 2 of the 3 primary germ layers are related to eye development?

dorsal; neural plate

The thickening of ectoderm is seen on the (dorsal/ventral) surface. This eventually forms the ______________.

neural folds

The ridges of the neural plate grow into the _____________. & grow towards each other

neural tube

What is the name of the structure that forms through the meeting of neural folds?

True

True/False: The neural tube fuses in both directions.

somites

Initial fusion of the neural tube happens around what part/structure?

neural crest cells

Just before neural tube fusion occurs, a section of cells on the crest of each fold separates from the ectoderm & form islands within the mesoderm. These cells are called ______________.

1. Surface ectoderm
2. Neural crest
3. Mesoderm
4. Neural tube of neural ectoderm

Identify the following structures of the developing neural tube.

neural ectoderm

What type of embryonic tissue makes up the neural tube?

mesoderm

What separates the neural ectoderm from the surface ectoderm once the neural tube forms?

1. Neural tube
2. Surface ectoderm
3. Neural crest cells
4. Mesoderm

At about 4 weeks in to embryogenesis, what 4 main structures are formed?

ectoderm

From what embryonic tissue do neural crest cells come from?

mesenchyme

Neural crest cells + mesoderm

mesenchyme

What is often referred to as embryonic connective tissue?

optic primordium

Thickened zone around the neural folds

optic grooves/sulci

As the nural plate thickens, before the groove turns into a tube, the ____________ start to form.

optic pits

What is the name given to the optic groove once it deepens?

neural crest cells

As the optic pit and the rest of the forebrain are pulled outwards, __________________ migrate in between the neural and surface ectoderm.

optic vesicles

Sac shaped extensions that are formed from the optic pits

neural tube

The optic pits is continuous with the lumen of the ________.

neural tube

Constriction of what tissue forms the optic stalk?

1. Forebrain
2. Lens placode
3. Optic vesicle
4. Mesenchyme
5. Surface ectoder,
6. Midbrain
7. Mesenchyme

Identify the missing structures of the expanded optic pit (1-7).

surface ectoderm

As the optic vesicle grows, it approaches the ___________.

retinal disc

What structure forms as a result of the vesicle starting to thicken and flatten?

optic cup

What forms as a result of the optic vesicle folding in on itself?

optic fissure

What structure prevents the optic cup from being able to hold water (if it could)?

mesoderm; hyaloid vascular system

The folding of the vesicle moving in on itself forms a fissure that allows ________ to enter the cup. What is the name of these mesodermic structures?

It fuses centrally, and moves anterior to posterior.

Once the hyaloid vascular system is present in the cup, the edges of the cup move towards each other and eventually fuse. How does it fuse to completion?

1. Outer layer of optic cup
2. Inner layer of optic cup
3. Lens vesicle
4. Optic fissure
5. Hyaloid vein
6. Hyaloid artery

Identify the following structures of the optic cup (1-6)

2; neural ectoderm; intraretinal space

Once the optic cup fuses its edges together, how many layers of cells are present? Where do both of these layers originate (embryologically)? What separates the 2 layers?

b. apical to apical

Which of the following options indicate how the optic cup edges align?

a. Basal to apical

b. Apical to apical

c. Basal to basal

retinal pigment epithelium/PCE/anterior iris epithelium; neural retina/NPCE/posterior iris epithelium

The outer and inner layer of the optic cup eventually contacts each other. The outer layer forms the ________________________. The inner layer forms the ______________________.

1. Lens placode/plate formation
2. Elongation of ectodermal cells
3. Increase in cell division

At the optic vesicle contacts the surface ectoderm, the surface ectoderm thickens. What 3 things happen after this?

lens pit

As the lens vesicle grows, what closes off and separates from the surface ectoderm (lens vesicle stage)?

lens capsule

The thin basal lamina left behind during the lens vesicle stage eventually develops into what structure?

primary vitreous; secondary vitreous

As the optic cup continues to fold after the lens vesicle stage, the lens vesicle begins to separate. What does this spaace began to fill with? What fills the space around 6 weeks after the primary vitreous?

posterior cells; retinal cells

To fill the space inside the lens vesicle, the __________ begin to grow, which is likely induced by signaling from the _____________.

primary lens fibers; embryonic nucleus

The posterior cells grow in order to fill the lens vesicle space. These cells form what fibers? These fibers make up the ________________.

1. Corneal epithelium
2. Lens equator
3. Vitreous body
4. Retina
5. Lens fibers
6. Lens epithelium

Identify the missing structures in the image.

optic fissure

Through what structure does the hyaloid artery enter the optic cup?

internal carotid

The hyaloid artery is a branch of the __________________ artery.

hyaloid artery

What vasculature fills the vitreous chamber with its dense branching network and forms the posterior vascular network of the lens?

Posterior tunica vasculosa lentis

What is the name of the posterior vascular network of the lens?

Week 6

Around what week of development does the optic fissure close?

month 3; months 8 & 9

During what month of development is the hyaloid vasculature at its peak function? What month is this vasculature absorbed?

lens vesicle; primary vitreous

At 5 weeks, the hyaloid vessels enter and fill much of the space between the _________ and the infolding early retina. By 2 months, the __________ is at its largest.

1. hyaloid
2. retina

By month 3, the primary vitreous is at its largest. The secondary vitreous begins to form peripherally between what 2 structures?

No; tertiary vitreous

By month 4 of ocular development, the hyaloid system atrophies and regresses. Does the secondary vitreous stop developing here? What begins to form at this time?

zonules

What is another name for tertiary vitreous?

RPE; neural retina

Two layers of the optic cup move towards each other in development. The outer layer will form the ______. The inner layer will become _________________.

1. Proliferative zone (outer)
2. Marginal zone (inner)

In the differentiation of the outer and inner layer of the optic cup, the cells proliferate (weeks 4-6) and form 2 zones. What are these 2 zones called? Indicate which is inner and which is outer.

marginal zone

Which is anuclear--proliferative zone or marginal zone?

1. Inner neuroblastic layer
2. Outer neuroblastic layer

Cell migration of the proliferative zone forms 2 nuclear layers in early retina development. What are these 2 layers?

centrally to peripherally

In the development of mature retina, cells differentiate moving (peripherally to centrally/centrally to peripherally).

central retina

What region of the retina develops first?

centrally to peripherally; optic nerve

Retinal arteries and veins develop (peripherally to centrally/centrally to peripherally). What lies in the center of retina arteries and veins?

temporal retina

What region of the retina is the last to get blood supply?

True

True/False: Like the optic cup, the optic stalk is double walled.

1. Mesenchyme
2. Hyaloid vessels

Glial cells

What 2 components are responsible for filling in the optic fissure as it forms? What do these develop into eventually within the optic nerve?

LGN

Ganglion cell axons fill in the fissure as they make their way back towards the _______.

surface ectoderm

What embryonic tissue starts the development of the cornea?

Break away of the lens vesicle

What induces the development of the cornea (epithelium specifically)?

Corneal endothelium forms (neural crest)

In the development of the cornea, what occurs in migration 1?

2 layers thick

The corneal endothelium starts out as how many layers thick?

Cells (keratocytes) migrate centrally from the limbus between epithelium and endothelium.

During corneal development, what occurs during migration 3?

keratocytes

What cells make the cornea stroma proper during corneal development?

iris stroma

The second migration of corneal development forms the _______________.

1. Cells will become the stroma of the iris
2. Cells will make up the pupillary membrane.

The second migration of corneal development provides what 2 things about the cells?

initial anterior vascular tunic

What does the pupillary membrane replace during ocular development eventually?

annular; iris stroma

Loop from ______ vessels disconnect and are reabsorbed as the lens thickens. Remnants are incorprated into the vasculature of the ___________.

peripheral

The more (central/peripheral) vessels contribute to the vasculature of the iris.

central to peripheral

The choroid develops from (central to peripheral/peripheral to central).

RPE

What structure induces mesenchymal cells to form the inner layers of the choroid?

smaller; larger

The development of the choroid starts at the inner, (smaller/larger) diameter vessels and proceeds outwards to (smaller/larger) diameter vessels.

anteriorly

The sclera first starts developing (posteriorly/anteriorly).

mesenchyme

Scleral development starts with _____________ cells that condense near the limbus.

optic nerve

At what structure does the sclera reach posteriorly and stops growing?

lamina cribrosa

Around the 4th month of development, the scleral fibers develop between the optic nerve fibers to form what structure?

optic cup

The epithelium of the ciliary processes are developed from the layers of what structure?

neural crest cells; ciliary muscle

What embryonic cells form the stroma of the ciliary body? Later on, these cells also form the _____________.

Most muscle is derived from mesoderm.

Why is it unusual for ciliary muscle to be derived from neural crest cells?

1. Lens
2. Cornea

Toward the end of the 3rd month of development, the tip of the optic cup grows between what 2 structures to form the epithelial layers of the iris?

1. Iris sphincter
2. Iris dilator

The epithelial layers of the iris will then ultimately produce what 2 muscles of the iris?

second migration

The stroma of the iris is derived from which migration of neural crest cells?

6

Pigment of the iris continues to develop for about ___ months after birth.

7 years

How many years can iris stroma continue to grow for?

surface ectoderm; mesenchyme

Eyelids are composed of what embryological tissue? What fills this tissue?