Lecture 2 Flashcards
Gestation period is how long?
40 weeks - varies depending on animal
Premature birth is before the ___ week
37th
_______ one of the most important events in prenatal development, and marks the beginning of rapid development of the embryo
Gastriculation
________ is the skin, hair, nail, sensory epithelia of the ear, eye, nose, and CNS and PNS.
Ectoderm
The mesoderm consists of what (7)?
- cartilage
- bone
- connective tissue
- smooth muscle
- heart
- kidney
- spleen
What does the endoderm consist of? (3)
- epithelial tissue of digestive and respiratory tract
- eustachian tube
- tympanic cavity
Which stage in embryology do these occur?
- All major organ system begin and undergo critical development
- embryo achieves human-like appearance
embryonic stage
Which stage in embryology do these occur?
- crucial development period
- most susceptible to teratogens
- exposure results in death or congenital anomalies affecting multiple organ systems
embryonic stage
Which stage in embryology do these occur?
- flat trilaminar disk folds into a cylindrical shape
- by the end of the ___th week, 4 pairs of branchial or pharyngeal arches are discernible
- otic pits (develop into the sensory structure of the inner ear) are visible as thickening on the lateral surface
embryonic stage
- 4th
Which stage in embryology do these occur?
- enlargement of the head an differentiation of structures in the limbs
- In the __th week, structures important to the fututre development of the external ear emerge.
- several small swellings (auricular hillocks) develop around the groove between the 1st and 2nd branchial arches
embryonic stage
6th week
Which stage in embryology do these occur?
In the __th week facial features are clearly distinguishable. Ears are low-set but show the EAC and auricles
embryonic stage
8th week
Which stage in embryology do these occur?
- rapid growth of body structures and growth and differentiation of tissues and major organ systems
- body growth acceleration occurs in the __th week
Fetal development
9th
in the __th week external ears become repositioned through growth of head
16th
during the __th week structures important to the future development of the external ear emerge
6th
major features of the ears, face, and palate differentiate primarily during the _th through __th week
4-8
Formation and evolution of the branchial arch during - weeks are major events in the development of the external and middle ear
- inner ear develops simultaneously but from different embryonic tissue
4-8 weeks
External initiated by formation of branchial arches.
Swellings around the 1st branchial arch around week _ grow and fuse to be a recognizable ear by about the _th week
- week 5
- - 8th week
Through the _th week of development the EAM is occluded by a solid tissue plug.
- EAM opens during the _ week
20th
21st
By the _ 1/2 weeks the incus and malleus have attained complete cartilaganeous form.
-all ossicles start to ossify during the _th month of development
- 8
- 4th
____ are the first bone in the human body to attain adult size
Ossicles
Inner ear development: Sensory structures derived from ectoderm tissue thickenings on lateral surface of head. The thickenings become apparent around the _th week
4
Inner ear development:
- In the _th week the cochlear pouch begins to coil
- in the _th week 1.5 coils are present
- in the _th week 2.5 coils are present
- The membraneous cochlea continues to grow through _ weeks
- 6th
- 8th
- 9th
- 16
Inner Ear Development:
In the _th - _th week sensory structures are developing from cells within the membranous labyrinth
• As the labyrinth development finalizes, 6 sensory structures develop
- three ampullae of the SCC
- the maculae of the saccule and utricle - organ of corti
17th-20th
- _ weeks- full number of adult hair calls is apparent
- _th week- mature synaptic patterns on the IHC
- Rudimentary functional hearing is achieved around the _th week
- _-_th week- OHC reach adult configuration
- _th week- cochlea has achieved its final size and structure - growth and development are COMPLETE
- 17
-20th
-20th
22nd-25th
34th
___ ___ only sensory organ to reach full adult size and differentiation by fetal midterm • Fully developed at birth
inner ear
Cochlea to cortex: - weeks: afferent connections from IHC to the brainstem are established - almost at same time- more central nuclei in the brainstem and auditory cortex are developed and connected
20-30
Constant stimuli needed for survival of neurons & synapses - intrinsic- spontaneous activity - extrinsic- acoustically drive activity
Cochlea to cortex
Fetal Response to Auditory Stimuli can do what?
Can evaluate hearing of a fetus with reflex responses
- startle
- body movement/ reduction in movement - auropalpebral reflex
- change in heart rate
Auditory System Malformations - name them
Auricular appendages/ skin tags
• Microtia
• Anotia
• Usually accompanied by malformations of the EAM ; ME
Three superimposed cellular plates, “germ cell layers” are established during ______. This occurs in the _______ stage and in week ___.
gastrulation
Pre-embryonic stage
3
What are the three germ layers established in gastrulation?
ectoderm, mesoderm, and endoderm
The skin, hair, nail, sensory epithelial, CNS and PNS are the ______
ectoderm
The mesoderm includes:
cartilage bone connective tissue smooth muscle heart kidney spleen
The endoderm includes:
epithelial tissue of digestive and respiratory tract
Eustachian tube
tympanic cavity
Three Stages:
- Pre-embryonic
- Embryonic
- Fetal
- 2-3 weeks
- 4th to 8th week
- 9 weeks to term
