Term
What are the three layers of the developing embryo? |
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Definition
Mesoderm
Ectoderm
Endoderm |
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Term
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Definition
used for the development of notochord, muscles, mesenchyme (→ dermis, circulatory system, and connective tissue) |
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Term
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Definition
surface ectoderm + neural ectoderm
involved in development of ocular structures, CNS, epidermis, skin, nail, hair |
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Term
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Definition
forms the gut, most glands and the inner lining of the digestive and respiratory tubes |
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Term
Describe how the neural tube is formed and what it consists of. |
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Definition
on the 18th day of development, two neural folds develop in the ectoderm that grow toward each other and fuse forming the neural tube.
it consists of the forebrain, mid brain and hindbrian |
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Term
What does the forebrain differentiate into? |
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Definition
Telencephalon and diencephalon |
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Term
What does the optic vesicles develop from? |
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Definition
Neural ectoderm, on the 25th day
it invaginates and forms a two layered optic cup with an optic stalk (which will become the optic nerve) and the fetal fissure (for the hyaloid artery and vein) |
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Term
What is the last structure to close during the formation of the optic cup?
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Definition
Embryonic fetal fissure
allows development of hyaloid artery plexus
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Term
What does the hyaloid artery plexus persist as after differentiation? |
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Definition
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Term
What happens if the fetal fissure fails to close? |
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Definition
A coloboma forms
choroid, retina, optic nerve, eyelids, iris or ciliary body are all possible locations and are usually found inferiorly |
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Term
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Definition
development of one tissue influences the development of another
(ex: optic cup formation stimulates lens development) |
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Term
Inner Layer of the Optic Cup |
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Definition
becomes neural retina, non pigmented CB epithelieum and posterior pigment layer of the iris |
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Term
Outer Layer of the Optic Cup |
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Definition
becomes the RPE, outer pigmented CB epithelium and anterior iris epithelium |
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Term
List the order of development of the cells within the neural retina |
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Definition
Ganglion
Horizontal
cones
amacrine
bipolar
rods
muller
RPE develops before these, the macula begins to differentiate first but it last to be complete |
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Term
When is foveal maturation complete? |
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Definition
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Term
What is the most common primary intraocular malignancy in children and how is it caused? |
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Definition
Retinoblastoma
occurs during development as a result of mutations in the Rb tumor suppressor gene |
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Term
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Definition
| surface ectoderm thickens and forms the lens placode, this invaginates forming a lens pit before becoming a lens vesicle as is separates from the surface ectoderm |
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Term
T or F
The posterior lens epithelium is present in adults. |
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Definition
FALSE
they differentiate into primary lens cells and elongate anteriorly as fibers to fill up the lumen, they produce crystallins during this process. |
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Term
T or F
Only the young, outer fibers are nucleated and contain organelles.
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Definition
TRUE
with age they lose their regularity and become less organized. their nuclei and organelles disintegrate. |
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Term
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Definition
contain the germative zone (anterior to the equator)
Becomes the secondary lens fibers which forms the fetal nucleus |
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Term
T or F
The embryonic nucleus contains Y sutures.
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Definition
FALSE
the Y sutures are from the secondary lens fibers and denote the boundaries of the FETAL nucleus. |
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Term
| Corneal epithelium is formed from... |
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Definition
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Term
| Corneal stroma and corneal endothelium are formed from... |
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Definition
neural crest cells
(a specialized type of neural ectoderm, they also contribute to cranial nerve formation) |
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Term
List the structures that form from
Surface Ectoderm |
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Definition
Corneal epithelium
lens
Lacrimal system (gland, sac, canaliculi, nasolacrimal duct, caruncle)
epithelium of Meibomian, Zeiss, Moll, Krauss and Wolfring glands
Conjunctival Epithelium |
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Term
List the structures that form from
Neural Ectoderm |
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Definition
Retina and RPE
Neuroglia
CB and Iris epithelium
sphincter and dilator muscles
optic nerve fibers
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Term
List the structures that form from
Neural Crest |
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Definition
4 layers of the cornea (everything except epi)
TM
CB and Iris Stroma
Sclera and Choroid
Vitreous |
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Term
List the structures that form from
Mesoderm |
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Definition
EOMs
Endothelium of blood vessels
Orbicularis oculi
levator palpebrae
Muller's muscle |
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Term
Most muscles come from mesoderm. What are the two exceptions to this rule?
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Definition
| Sphincter and Dilator muscles |
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Term
| Irregular corneal adhesions in conditions like Axenfeld's or Reiger's are due to... |
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Definition
| abnormal neural crest cell development |
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Term
| Two signs commonly noticed in congenital glaucoma are... |
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Definition
Corneal haze
Buphthalmos (enlarged eye before age 3) |
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Term
| Congential glaucoma is a result of... |
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Definition
| poor development of the angle architecture |
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Term
What are the effects of congenital glaucoma on the eye?
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Definition
↑IOP
Optic Nerve damage
Haab's Striae (folds in Descemet's)
high myopia
subluxation of the lens (rare) |
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Term
What combines to form connective tissue of the globe and the orbit?
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Definition
| neural crest cells and mesoderm |
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