Term
early development
3-5 days |
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Definition
blastomeres grow and become hollow
uterine liquids leaked to inside
blastomeres become blastocyst |
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Term
early development
6-8 days |
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Definition
blastocyst attaches to uterine wall
trophoblast starts becoming umbilical cord |
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Term
early development
9-12 days |
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Definition
maternal blood supply established
GASTRICULATION occurs |
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Term
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Definition
all embryo's must undergo gastriculation
blastopore appears and inner cell mass goes outside, outer cell mass goes inside
now cells divide at much faster rate
afterward, embryo organizes self into 3 germ layers: endoderm, mesoderm, ectoderm |
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Term
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Definition
somites begin to appear
somites=paired body parts
accurate way of telling embryo's age
ectoderm forms neural plate, then neural groove |
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Term
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Definition
neural groove closes over self and becomes neural tube
rostral surface of neural tube becomes neural crest |
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Term
inner ear development
week 3 |
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Definition
- otic pit forms
- appears as small indentatioon on both sides of embryo's head
- developed out of ectoderm
- as neural groove gets deeper, so does otic pit
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Term
inner ear development
week 4 |
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Definition
otocyst forms
round, liquid-filled bubble buried inside
as soon as otocyst forms, it begins to elongate |
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Term
inner ear development
week 6 |
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Definition
vestibular organs form
begins with semicircular canals |
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Term
inner ear development
week 7 |
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Definition
cochlea forms at bottom of otocyst
cochlea coils itself once |
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Term
inner ear development
week 11 |
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Definition
| VIIIth nerve attaches to cochlea |
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Term
inner ear development
week 12 |
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Definition
sensory cells appear in cochlea
in cochlea, membranous labyrinth completely formed
otic capsule (bone that surrounds inner ear) begins to ossify |
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Term
inner ear development
week 20 |
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Definition
sensory and supporting cells fully formed
inner ear now functional |
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Term
middle ear development
week 3 |
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Definition
middle ear develops @ top of primitive gut
tubotympanic recess forms at top of throat
recess begins to elongate latterally to become Eustachian tube |
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Term
middle ear development
week 4 |
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Definition
branchial grooves and arches appear
arch I: mandibular arch
arch II: hyoid arch |
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Term
middle ear development
week 8 |
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Definition
tubotympanic recess has extended from upper throat to middle ear
at far end of tube, lower half of tympanic cavity formed
cavity made of endoderm
migrating mesoderm cells become ossicles
cells from mandibular arch reach tympanic cavity to become malleus and incus |
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Term
middle ear development
week 9 |
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Definition
| 3 germ layers make up tympanic membrane |
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Term
middle ear development
week 15 |
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Definition
| stapes forms from migrating cells from Hyoid arch |
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Term
middle ear deveopment
week 16 |
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Definition
| malleus and incus begin to ossify |
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Term
middle ear deveopment
week 18 |
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Definition
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Term
middle ear development
week 21 |
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Definition
meatal plug disintegrates, exposing TM in ear canal
now have patent ear canal
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Term
middle ear development
week 32 |
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Definition
| ossification of malleus and incus complete |
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Term
middle ear development
week 34 |
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Definition
mastoid air cells develop
when still fetus, these cells filled w/liquid |
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Term
outer ear development
week 4 |
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Definition
| branchial arches and grooves appear |
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Term
outer ear development
week 5 |
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Definition
| external ear canal begins to form |
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Term
outer ear development
week 6 |
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Definition
6 hillocks appear on first 2 arches
(3 on each arch) |
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Term
outer ear development
week 8 |
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Definition
| lateral cartilaginous 1/3 of ear canal formed |
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Term
outer ear development
week 20 |
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Definition
pinna completes mature shape
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Term
postnatal development
to 2 years |
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Definition
| Tm becomes more vertical in orientation |
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Term
postnatal development
to 7-10 years |
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Definition
pinna continues to grow to mature size
ear canal elongates and becomes more twisted in shape
ET tube elongates
from anterior-medial angle to anterio-inferior-medial angle |
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Term
postnatal development
to 18 years |
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Definition
| stapes continues to ossify |
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