Eye and Ear Flashcards
What occurs as neural tube closes?
Paired optic sulci form optic vesicles
What are optic vesicles initially continuous with?
Forebrain cavity
What induces overlying ectoderm to grow, thicken and form the lens placodes?
Neural ectoderm
What connects each vesicle after lateral expansion?
Optic stalk
What occurs to the optic vesicle and overlying placodes?
Become concave and invaginate
What forms the optic cup?
A double layer of neural ectoderm
What allows for optic fissure to form?
More ventral invagination of optic vesicle and lens placodes
What forms the future optic nerve?
Optic fissure closes around hyaloid vessles and the vessels are enclosed in optic stalk
What does the fissure closure allow?
Intraocular Pressure to be established in closed optic cup
Formation of furture optic nerve
What forms with lens placode invaginating into optic cup?
Forms a lens vesicle
What marks beginning of formation of eye chambers?
When vesicle detaches from surface ectoderm
2 things which constitutes formation of eye chambers?
Lens becomes surrounded by mesenchyme
Lens vesicle positioned in front of opening of optic
What occurs right after vesicle formation?
Epithelial cells of posterior wall elongate and grow towards anterior wall
2 features of primary lens fibres?
Contain large quantities of proteins, Crystallins
Lose organelles leaving basic cytoskeloton and transparent cytoplasm
From where does the new population of secondary lens fibers develop?
Develop from the epithelial cells of the anterior wall of the vesicle
What do the secondary lens fibres form?
Concentric layers around the primary fibres of the embryonic lens nucleus
From what does the retina differentiate
Apposed walls of optic cup
What does the outer wall of optic cup contribute to the retina?
Thin pigmented layer of retina and ciliary body and iris
What does the inner wall of the optic cup contribute to the retina?
Visual area of retina.
Neuroepithelial cells grow and differentiate into layers
- Rods
- Cones
- Bipolar and Ganglion cells
- Supportive glial cells
In the functional eye, what will light pass through?
Inner layers of the retina before reaching visual receptors
Follow pathway of signalling
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
Where is the reflective layer in domestic animals eye found?
Choroidal layer
what makes up the tapetum lucidum?
Flat cells packed with crystalline rods
What does the tapetum lucidum of herbivores consist of?
Collagen fibers and fibrocytes
Where is the vitrous body located and what is it made up of?
Between retina and lens
Neural crest derived mesenchyme migrates between retina and lens
Where is the cornea located and what is it made up of?
Mesenchymal cells form two layers between lens and surface ectoderm
What do mesenchyme around the region of the ciliary processes and covering non-visual retina provide?
Vascular supply with blood vessel formation
What makes up the suspensory ligament of the lens?
Mesenchymal cells which develop into radially arranged fibers
What controls shape of lens?
Ciliary muscles in mesenchyme in connection with suspensory ligament
