Weekly Development Flashcards
1-6 EL
Conception- zygote- blastomere
6-8 EL
Blastomere adheres to uterine wall
9-12 days EL
Gastrulation occurs
What happens at 12 days of EL?
Maternal blood supply, gastrolation, and 3 germ layers
After 12 days of EL what do we have?
3 germ cell layers
What are the 3 germ cell layers
Endoderm, mesoderm, ectoderm.
After gastrulation why does the embryo become fragile?
- Specialized cells have specific duties
- Very few specific types
- Subtypes appear quickly
- One specialized cell cannot substitute for another damaged specialized cell.
3rd week of Embryo life
Somites begin to develop and ectoderm forms.
What happens during the 4th week of embryo life?
30 somites and head, heart beat, and tail.
What happens during week 3 of ear development.
Inner: Otic pit forms
Mid: tubotympanic recess begins.
What happens during the 4th week of ear development.
Inner: otic cyst forms
Mid and outer: branchial grooves/ arches appear.
What happens during the 5th week of ear development?
Outer: external ear canal begins to form.
What happens during week 6 of ear development.
Inner: Vestibular organs begin to form 3 semicircular canals.
Outer: 6 hillocks appear on mandibular and hyoid arches. Cartilage begins to form.
What happens during week 7 of ear development.
Inner: cochlea elongates to one coil. Sensory cells in vestibular organ begins to form.
What happens during week 8 of ear development
Mid: lower half of tympanic cavity is formed by extended tubotympanic recess. Migrating cells from branchial arches form malleus and incus.
Outer: lateral cartilaginous 1/3 of ear canal formed.
