Eye and Ear

Question 1

What occurs as neural tube closes?

Answer 1

Paired optic sulci form optic vesicles

Question 2

What are optic vesicles initially continuous with?

Answer 2

Forebrain cavity

Question 3

What induces overlying ectoderm to grow, thicken and form the lens placodes?

Answer 3

Neural ectoderm

Question 4

What connects each vesicle after lateral expansion?

Answer 4

Optic stalk

Question 5

What occurs to the optic vesicle and overlying placodes?

Answer 5

Become concave and invaginate

Question 6

What forms the optic cup?

Answer 6

A double layer of neural ectoderm

Question 7

What allows for optic fissure to form?

Answer 7

More ventral invagination of optic vesicle and lens placodes

Question 8

What forms the future optic nerve?

Answer 8

Optic fissure closes around hyaloid vessles and the vessels are enclosed in optic stalk

Question 9

What does the fissure closure allow?

Answer 9

Intraocular Pressure to be established in closed optic cup

Formation of furture optic nerve

Question 10

What forms with lens placode invaginating into optic cup?

Answer 10

Forms a lens vesicle

Question 11

What marks beginning of formation of eye chambers?

Answer 11

When vesicle detaches from surface ectoderm

Question 12

2 things which constitutes formation of eye chambers?

Answer 12

Lens becomes surrounded by mesenchyme

Lens vesicle positioned in front of opening of optic

Question 13

What occurs right after vesicle formation?

Answer 13

Epithelial cells of posterior wall elongate and grow towards anterior wall

Question 14

2 features of primary lens fibres?

Answer 14

Contain large quantities of proteins, Crystallins

Lose organelles leaving basic cytoskeloton and transparent cytoplasm

Question 15

From where does the new population of secondary lens fibers develop?

Answer 15

Develop from the epithelial cells of the anterior wall of the vesicle

Question 16

What do the secondary lens fibres form?

Answer 16

Concentric layers around the primary fibres of the embryonic lens nucleus

Question 17

From what does the retina differentiate

Answer 17

Apposed walls of optic cup

Question 18

What does the outer wall of optic cup contribute to the retina?

Answer 18

Thin pigmented layer of retina and ciliary body and iris

Question 19

What does the inner wall of the optic cup contribute to the retina?

Answer 19

Visual area of retina.

Neuroepithelial cells grow and differentiate into layers

• Rods
• Cones
• Bipolar and Ganglion cells
• Supportive glial cells

Question 20

In the functional eye, what will light pass through?

Answer 20

Inner layers of the retina before reaching visual receptors

Question 21

Follow pathway of signalling

Answer 21

Impulses generated in rods and cones move to overlying bipolar neurons and then ganglion cells

Axons of ganglion cells move into optic stalk and become optic nerve

Question 22

Where is the reflective layer in domestic animals eye found?

Answer 22

Choroidal layer

Question 23

what makes up the tapetum lucidum?

Answer 23

Flat cells packed with crystalline rods

Question 24

What does the tapetum lucidum of herbivores consist of?

Answer 24

Collagen fibers and fibrocytes

Question 25

Where is the vitrous body located and what is it made up of?

Answer 25

Between retina and lens

Neural crest derived mesenchyme migrates between retina and lens

Question 26

Where is the cornea located and what is it made up of?

Answer 26

Mesenchymal cells form two layers between lens and surface ectoderm

Question 27

What do mesenchyme around the region of the ciliary processes and covering non-visual retina provide?

Answer 27

Vascular supply with blood vessel formation

Question 28

What makes up the suspensory ligament of the lens?

Answer 28

Mesenchymal cells which develop into radially arranged fibers

Question 29

What controls shape of lens?

Answer 29

Ciliary muscles in mesenchyme in connection with suspensory ligament