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Week 3
Otic Placode and Otic Vesicle Form -
Week 5
Cochlear part of otic vesicle elongates -
Week 9
Mesenchyme surrounding membranous labrynth chondrifies -
Weeks 12-16
Capsule adjacent to membranous labrynth undergoes vacuolization to form a cavity (perilymphatic space) around membranous labrynth and fills with perilymh -
2nd Trimester
Centres of ossification appear in remaining cartilage of otic capsule form petrous portion of temporal bone. This continues to ossify to form mastoud procoss of temporal bone. -
3rd Trimester
Vibration acoustically of maternal abdominal wall induces startle response in infants
