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20 Cards in this Set
- Front
- Back
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When does the development of the eyes begin?
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4th week.
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What is a general pattern for eye development in terms of signaling?
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The eye develops via inductive messages.
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Where do the eyes develop from? Describe the process.
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A population of cells in the anterior neural plate.
These cells make up the eye field in the prosencephalon (forebrain). Rapid growth of the prosencephalon carries this region of the brain forward. OPTIC GROOVES (sulci) form as cells begin to infold. The edges of the cranial neural folds approach the midline, and THE NEUROECTODERM OF THE OPTIC GROOVE COMES INTO CLOSE CONTACT WITH ECTODERD --> induction of lens placode. INSTRUCTIONS TO FORM LENS PLACODE COMES FROM OPTIC VESICLE. Lense placode and optic vesicle infold. The lens placode pinches off the ectoderm. infolding of the optic vesicle give the OPTIC CUP which remains connected to the forebrain via the OPTIC STALK. |
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Placode
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Ectodermal cells that form small aggregates which are incorporated into surface ectoderm. This forms sensory organs.
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What encloses the hyaloid artery in the early development stages of the eyes?
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Inner layer and outer layer of optic stalk.
Remember, the inner layer becomes the optic nerve. The hyaloid artery becomes the central retinal artery and vein. |
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In the development of the eye, what happens to the hyaloid artery?
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It becomes the central retinal artery and veins.
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In the development of the eye, what happens to the inner layer of optic stalk?
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Optic nerve.
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What is the fissure called between the inner and outer layers of the optic stalk?
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Choroidal fissure. This closes as the inner and outer layers of the optic stalk fuse.
Clinical correlation: persistent choroidal fissure. Characterized by keyhole shaped pupil. |
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What temporarily supplies blood to the lens and vitreous chamber?
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Hyaloid artery (which will later be obliterated and turn into central retinal artery and vein in optic stalk).
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What happens to the pigmented layer and neural portion of the retina as they develop?
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The pigmented layer becomes relatively thinner, while the neural portion becomes thicker.
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Where do the iris and ciliary body body develop from?
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Anterior rim of optic cup. Therefore, the ciliary muscles are derived from the neural ectoderm.
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What is the master regulator gene of the eye?
Where is it expressed? |
PAX 9.
Expressed in ectoderm near optic vesicle. |
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What does the cornea develop from?
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Cornea develops from outer epithelial layer, and inner layer derived from neural crest cells.
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When does the inner ear begin to develop?
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Week 3.
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What structure does the inner ear develop from?
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Otic placode of the hindbrain (specialized ectoderm).
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Otic vesicle develops into what three structures?
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Three major subdivisions of the inner ear:
Endolymph sac and duct. Utricle Saccule: outgrowth of this forms cochlear duct. |
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What structure forms the middle ear?
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neural crest cells.
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What forms the tympanic membrane?
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Pharyngeal membrane 1 (mesenchyme with flanking ectoderm and endoderm).
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What structure forms the external ear?
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Pharyngeal groove 1 forms external auditory meatus.
Six mesodermal mounds (3 from 1st pharyngeal arch, and 3 from 2nd) form the pinna (auricle) of the ear. The lobule of the ear is NOT derived from the hillocks. |
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What structure forms the olfactory system?
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Olfactory placodes on the frontonasal prominence.
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