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48 Cards in this Set
- Front
- Back
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Embroyo
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first 8 weeks of gestation
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Zygote
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fertilized ovum; @ approx. 20 hours
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When does the zygote divide for the first time?
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a few hours after the nuclei has fused
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How often does the cell divide as it continues down the fallopian tube?
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every 12-15 hours
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Morula stage: what is it? when does it occur?
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ball of cells, approx. two days after conception
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Blastula Stage: what is it? when/where does it occur?
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-when cavity in ball of cell forms, approx. 4 days, located in uterus
-begins to differentiate b/w placenta & embroyo, implants in uteran wall |
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Neural Tube: when does it occur?
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-@ approx. 3 weeks
-top of tube becomes brain -swellings on side become branchial arches |
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Embryonic development occus along ______. What are they?
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-three germ cell layers
-ectoderm, mesoderm, endoderm |
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What does ectoderm become (in general)?
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outer skin, nervous system, & sense organs
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What does mesoderm become (in general)?
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circulation structures, reproductive organs, & skeltal structures
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What does endoderm become (in general)?
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digestive system & respiratory system
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What does ectoderm become (in auditory system)?
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outer ear, lateral layer of TM, membranous labrinyth, & organ of corti
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What does mesoderm become (in auditory system)?
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ossicles, temporal bone, fibrous layer of TM
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What does endoderm become (in auditory system)?
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tympanic cavity, eustachian tube, medial layer of TM
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Auricle Development: Week 3-4
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tissue thickenings begin to form
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Neural Tube: when does it occur?
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-@ approx. 3 weeks
-top of tube becomes brain -swellings on side become branchial arches |
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Embryonic development occus along ______. What are they?
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-three germ cell layers
-ectoderm, mesoderm, endoderm |
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What does ectoderm become (in general)?
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outer skin, nervous system, & sense organs
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What does mesoderm become (in general)?
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circulation structures, reproductive organs, & skeltal structures
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What does endoderm become (in general)?
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digestive system & respiratory system
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What does ectoderm become (in auditory system)?
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outer ear, lateral layer of TM, membranous labrinyth, & organ of corti
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What does mesoderm become (in auditory system)?
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ossicles, temporal bone, fibrous layer of TM
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What does ectoderm become (in auditory system)?
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tympanic cavity, eustachian tube, medial layer of TM
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Auricle Development: Week 3-4
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tissue thickenings begin to form
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Auricle Development: Week 6
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-tubercles form out of hillocks each arch on each side of branchial groove
-cartilage begins to form |
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Auricle Development: Week 7
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-Auricle moves dorsolaterally
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Auricle Development: Week 8
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-Outer 1/3 of cartilaginous EAC formed
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Auricle Development: Week 20
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-Auricle adult shaped but grows until age 9
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Auricle Developmen (EAC)t: Week 21
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-Meatal plug disintegrates exposing TM
-EAC continues to develop until 7 yrs. |
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Middle Ear Development: Week 3
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-ME cavity & tube form from endoderm tissue
(Tympanic cavity [tubotympanic] recess begins to develop) |
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Middle Ear Development: Week 5-6
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-ossicles begin to develop from mesoderm in branchial arches 1 & 2
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Middle Ear Development: Week 8
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-Incus & Malleus form from mesoderm
-lower 1/2 of tympanic cavity formed |
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Middle Ear Development: Week 9
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-3 layers of TM present
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Middle Ear Development: Week 15
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-Stapes present in cartilaginous form
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Middle Ear Development: Week 16
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-Ossification of malleus & incus begins
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Middle Ear Development: Week 18
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-Ossification of stapes begins
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Middle Ear Development: Week 21
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-TM is formed when meatal plug (ectoderm) disintegrates
-change position until year 2 |
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Middle Ear Development: Week 22-30
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-Pneumatization of tympanum
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Middle Ear Development: Week 32
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Malleus & incus ossify completely
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Middle Ear Development: Week 34-37
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-Mastoid air cells develop
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Inner Ear Development: Week 3-4
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-begins to develop from ectoderm on both sides of neural tube
-auditory placode begins to grow into mesoderm -vestibular-cochlear division |
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Inner Ear Development: Week 6
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-Utricle & saccule form
-SCC begin |
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Inner Ear Development: Week 7
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-1 cochlear coil
-sensory cells in ut & sacc |
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Inner Ear Development: Week 8
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-sensory cells SCC
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Inner Ear Development: Week 11
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- 2 1/2 cochlear coils
-cochlear duct attaches to nerve VII |
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Inner Ear Development: Week 12
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-sensory cells in cochlea
-membranous labrinth formed (out of otocyst) -otic capsule begins to ossify |
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Inner Ear Development: Week 20
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-maturation of IE
-IE adult size |
