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HNSS > 12-Embryology of the eye and ear brainscape > Flashcards

12-Embryology of the eye and ear brainscape Flashcards

1
Q

Coloboma

A

incomplete closure of optic fissure. Often associated with Pax-2 abnormalities and kidney disease

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2
Q

Crystallins

A

proteins in primary lens fibers that allow for refraction & focusing of light rays

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3
Q

Describe the initial development of the ear

A

FGF3 + FGF 10 –> Thickening of ectoderm to produce the otic placode

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4
Q

Development of the Ciliary Body

A

*Neuroectoderm & mesoderm *Located between the iris & neural retina, arises from point where the neural and pigment retinas meet at outer rim of optic cup

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5
Q

Development of the Iris

A

arises from point where neural and pigment retinas meet (it is therefore mesoderm & neuroectoderm) *Through contraction & relaxation, controls amount of light that passes through the pupil

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6
Q

Differentiation of the Cornea

A

Induced by the formation of the lens at week 8 *Outer epithelial layer from surface ectoderm and inner layer from NC cells

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7
Q

Formation of the eyelids

A

*From ectodermal-mesenchymal folds *Fuse at 10 weeks, lead to formation of conjunctival sac underneath *Reopen at beginning of third trimester

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8
Q

Formation of the Otic Pit

A

otic placode invaginates into the mesenchyme

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9
Q

From what tissue does the optic groove form?

A

Neuroectoderm

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10
Q

From which location do eye fields develop?

A

from cells in the anterior neural plate - in the prosencephalon

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11
Q

How do we have separate eyes?

A

Eye fields develop in areas that express Pax-6 BUT: cells in midline express SHH which represses Pax -6 so we have separate optic fields

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12
Q

How does the bony labyrinth form?

A

membranous labyrinth is initially surrounded by NC cells that form mesenchymal covering. Mesenchyme becomes cartilaginous, then ossifies. Mesenchyme closest to labyrinth degenerates, forming the perilymphatic space that contains the perilymph

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13
Q

How does the lens placode form and from what tissue?

A

FGF & BPM from neuroectoderm of optic vesicle + Sox 2 + Pax 6 –> Thickening of the surface ectoderm –> Lens placode

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14
Q

Hyaloid vessels

A

located within the choroid fissure in the optic stalk - supply the neural retina & developing lens *Past 10 weeks the vessels degenerate, but the central artery of the retina is left behind (branch off the opthalamic artery off the ICA)

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15
Q

Location of the Otic Vesicle

A

Dorsal to the second pharyngeal cleft Adjacent to the rhombencephalon Very close to the neural tube

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16
Q

Optic Chiasm

A

nerve fibers from each half of the retina cross over–> allows each half of brain to receive visual signals from visual fields of both eyes

17
Q

Outer vs Inner Layer of the Optic Cup

A

Outer Layer= Pigmented epithelium Inner Layer= Neural retinal cells

18
Q

Perilymph

A

Located in the perilymphatic space which floats the membranous labyrinth within the bony labyrinth. Communicates with the subarachnoid space via the perilymphatic duct

19
Q

Persistent Pupillary Membrane

A

can interfere with vision by reducing the amount of light passing through the eye or cause stimulus deprivation (ambylopia)

20
Q

Pigmented epithelium

A

monolayer of pigmented cells that helpt o reduce scattered light. Secretes growth factors, and is the reason why pupils are black

21
Q

Primary Lens Fibers

A

cells at posterior surface of the lens vesicle. Elongate, lose their pigment, and express crystallins *Lose nuclei, form lifeless cell and remain at center of lens for life *SIze of lens determined by cell proliferation at lens vesicle’s equator

22
Q

Pupillary membrane

A

membrane located between the anterior & posterior chambers *Will atrophy between time of birth and 4-6 weeks postnatal

23
Q

Secondary Lens Fibers

A

*Form after 8th week, simple epithelium at anteiror wall form these new fibers. Contribute to the growth and maintenance throughout life

24
Q

What does Pharyngeal Arch 1 give rise to in the middle ear?

A

Malleus, Incus (both from Meckel’s cartilage) and Tensor Tympani Muscle

25
Q

What does pharyngeal Groove 1 (aka pharyngeal cleft) form in the ear

A

External auditory meatus

26
Q

What does the Otic Vesicle give rise to?

A

All components of the membranous labrynth 1) Utricular portion 2) Saccular portion *Connected by the endolymph duct & sac

27
Q

What does the Pharyngeal Arch 2 give rise to in the middle ear

A

Stapes (from Reichert’s cartilage) and the stapedius muscle

28
Q

What does the Pharyngeal membrane 1 give rise to in the middle ear?

A

Tympanic membrane- separates the middle ear from the external auditory meatus of the external ear (innervated by CN V3 & CN IX)

29
Q

What does the Pharyngeal pouch give rise to in the middle ear?

A

Auditory tube & middle ear cavity

30
Q

What does the saccular portion of the otic vesicle give rise to?

A

1) Saccule 2) Cochlear Duct (organ of Corti) 3) Spiral ganglion of CN VIII

31
Q

What does the Utricular portion of the otic vesicle give rise to?

A

1) Utricle 2) Semicircular ducts 3) Vestibular ganglion of CN VIII 4) Endolymphatic duct & sac

32
Q

What factors control whether the optic vesicle becomes optic stalk or retina

A

Cells with High concentration of SHH –> Inhibition of Pax 6, Pax 2 is induced in optic stalk Cells with Low concentration of SHH –> permission of Pax 6, retina is induced

33
Q

What factors influence the growth of lens fibers?

A

Sox 2 Pax 6 Maf

34
Q

What is the innervation of the Auricle

A

CN V3 CN VII CN IX CN X and cranial nerves C2 & C3

35
Q

What is the innervation of the external auditory meatus

A

CN V3 & CN IX

36
Q

What structures arise from the Mesenchymal capsule of the optic vesicle

A

1) Choroid (analogous to pia mater of brain) 2) Slcera (analogous to dura mater of brain) 3) Anterior chamber = space between lens & cornea

37
Q

What will the optic groove give rise to?

A

1) Optic Stalk 2) Optic Vesicles

38
Q

Where are the places where the connection between the pigmented epithelim and neural retinal cells is strong? Implications of this?

A

Ora Serrata Optic Disc Fovea **Blow to the eyes or head can lead to retinal detachment

HNSS (17 decks)

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