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51 Cards in this Set
- Front
- Back
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The eye forms from two precursors:
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Ectoderm and Head Mesoderm
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The very first step of eye development:
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Optic grooves on the neural folds expanding into the Diecephalon (day 22, step 1)
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Expansion of optic grooves into the mesenchyme ultimately reaches the other side to reach the surface ectoderm. When this happens, what forms?
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Surface ectoderm begins to swell, forming the lens placode (step 1)
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What does the lens placode begin to do? What does this form?
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Signals the optic vesicle to invaginate - forming the lens vesicle (step 2)
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As the optic vesicle and lens vesicle continues to invaginate, what happens?
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The lens separates from the surface ectoderm (step 3)
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After lens separates from the surface ectoderm, what happens/forms?
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Surface ectoderm thickens AGAIN to form the Corneal Placode.
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See pg 2 of notes re different TF for different tissues:
Inner layer: ? Outer layer: Pigmented retina: ? Optic Stalk:? |
Inner layer: Pax6, Rx and others
Outer layer: Pigmented retina: Otx, Mit Optic Stalk: Pax2 |
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What is Anophthalmia?
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Total absence of ocular structures
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What is Microphthalmia? What is its genetic inheritance? What might it be due to?
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Small eye. Autosomal recessive. Possible due to defect in Pax6
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What is Primary Anopthalia?
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Small eye restricted to eye alone. Surrounding structures normal
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What is Secondary Anopthlamia?
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Defect is secondary to the forebrain defect such as holoprosencephaly.
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Outer layer of the optic cup forms:
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Pigmented Retina (sclera)
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Inner layer of optic cup forms:
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Sensory Portion of retina (4/5) and structures of front of eye (1/5) to include the iris and ciliar body
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The inner layer sensory portion of the retina is formed from what (this makes sense)
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neuropithelium
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The optic cup continues to grow around the vesicle to ultimately form what?
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The ciliary layer and the iris
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Surprisingly, what forms the fibers that attach to lens and accommodate?
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The ciliary body.
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What forms the ciliary mucle?
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NCC that migrate into the ciliary body.
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What part of the optic cup forms the iris? What forms the pigment portion of the iris?
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The ectodermal inner layer (p5 of notes). The outer layer of the Optic Cup forms the pigment portion of the iris.
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What tissue is the Anterior Corneal Epithelium derived from?
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Surface ectoderm (p. 8 notes)
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How does the white portion of the eye form (conjuctiva)
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Surface ectoderm migrates inside eye lid and around eye ball.
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See pg 9 for this:
What forms: Anterior corneal epithelium? Corneal Epi? Corneal stroma? Conjunctiva? |
See pg 9 for this:
What forms: Anterior corneal epithelium - surface ectoderm Corneal Epi - NC ectomesenchyme Corneal stroma - head meso Conjunctiva - surface ecto |
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What does the arteriol supply of eye form from?
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Chorioid fissure.
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Describe general process of arteriol supply formation.
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Begins at chorioid fissure of optic cup. Forms plexus within inner layer of optic cup. Passes through vitreol fluid to forma plexus that surrounds the lens. Plexus disappears, proximal portion continues to serve retina
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What is it called when the hyloid vascularture plexus does not disappear as it should?
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Persistent pupillary membrane
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What is the anterior chamber of the eye and how does it form?
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It is in front of the lens and forms via loose mesenchyme that eventually hollows out.
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What is the posterior chamber and how does its vitreous body form?
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It is between the retina and lens - mesenchymal cells here secrete extracellular matrix and fibrous extracellular matrix to form vitreous body.
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What does tim's nephew have?
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Coloboma
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Congenital ptosis of the eyelide could be caused by (two things):
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Neurological problem
Smooth muscle problem |
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What is the middle ear composed of?
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Ear drum and ossicles
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The outer ear is formed from three swellings called:
What tissue are they made from? |
Auricular Hillocks; Mesenchyme swellings. There are 3 anterior and 3 posterior swellings.
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What arches are the anterior and posterior auricular hilloks derived from?
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1st and 2nd, respectively
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Arch 1 hillock forms:
Arch 2 hillock forms: |
1 = Tragus and part of helix
2 = Remainder of auricle |
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The Cartilagenous portion of the external auditory meatus is formed by and during week:
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1st Pharyngeal groove at week 6
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The osseous portion of the external auditory meatus is an extension of:
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the 1st groove
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How does the ear drum form?
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The flattened medial end of the 1st groove extension become this tissue.
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What forms the Pharyngeal Tympanic Recess and ultimately, what does it become?
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Formed by the gut and therefore lined with endoderm. It forms the acoustic canal.
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Very generally, what two things meet up to form the middle ear?
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The 1st pharyngeal groove and the Pharyngeal Tympanic Recess
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What/how are the ossicles formed?
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They are formed from mesenchymal condensations that associate with the expansion of the Pharyngeal Tympanic Recess
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What middle ear components form from the 1st pharyngeal arch? 2nd arch?
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1. Malleus & Incus
2. Stapes |
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Describe the 3 layer components of the tympanic membrane
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Outer layer of ectoderm
Inner layer of endoderm Middle layer of mesenchyme More specifically: a. Epidermis = meatal plate (plug) b. Mesenchyme = stroma c. Mucosal Epi = pouch 1 lining (makes sense! GI is mucosal too) |
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Where does the tissue for the inner ear come from?
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The mesenchyme that associates with the Pharyngeal Tympanic Recess
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Where does the formation of the inner ear begin? What does it form? Where does it end up?
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As a thickening on the neural fold called the otic placode. Forms an otic vesicle that separates and comes to lie adjacent to the rhombencephalon.
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The otic vesicle forms the Membraneous Labyrinth. What's inside that and what is it covered with?
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Semicirular ducts, Utricle, Saccule and Cochlear Duct. All are covered with epithelial spaces
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What is the Membranesou Labyrinth enclosed by? What does it develop from?>
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The Osseous Labyrinth (Periotic Mesoderm) - developed from mesoderm that forms cartilage and then bone.
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The Osseous Labyrinth has three components:
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1. Semicircular Canals (containing semicircular ducts)
2. Vestibule (containing urtricle and saccule) 3. Cochlea (with cochlear duct) |
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The otic vesicle has a dorsal and ventral portion. What is the fate of the dorsal part?
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V = Cochlea
D = Semicircular canals |
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What is the spectrum of external ear sizes called?
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Anotia to Microtia Spectrum
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What is it called when the ears don't move to their proper location when there is no jaw?
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Otocephaly
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What are the two names given when a canal never forms?
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Meatal Atresia or Hypoplasia
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What are the three possible means to congentical hearing loss?
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Conduction; Sensorineural; Mixed combination
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What are the four possible causes of congenital hearing loss?
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1. Hereditary 2. Prenatal infection 3. Environmental 4. Unknown
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