Lecture2 Flashcards
What rotation occurs during fetal development?
the lower extremity rotates
During fertilization, how is egg brought to Fallopian?
picked up by fimbria, directed to opening of Fallopian tube
Enables Sperm to Enter Egg
lytic enzymes in the acrosome
DNA joining from egg and sperm timing
24 hours post-fertilization
First Week of Development
Day 1-fertilization, Day 2-first mitotic cycle, Day 3-morula development, Day 5-cell differentiation within morula to form inner cell mass, Day 6-7-late-stage blastocyst
Day 2 - First Mitotic Cycle
sperm and egg haploid DNA to the diploid, second mitotic cycle by the end of Day 2
Day 3 - Morula Development
16 cell cluster has genetic makeup to create every cell of body (stem cells)
Day 5 - Differentiation of Morula
inner cell mass will develop into embryo, entering uterus, thickened uterine walls have developed rich blood supply and glands for nutrition (must occur PRIOR to implantation)
Blastocyst
embryoblast (inner cell mass) and blastocyst cavity within the trophoblast membrane
Week 2 Inner Cell Mass Differentiation
2 cell layers: epiblast and hypoblast (also there is an amniotic cavity and the primary yolk sac–anyone else craving an omelet?
Gastrula Phase
end of 2nd week, 3 cell layers (epiblast/ectodermal, mesoderm, hypoblast/endodermal)
Gastrula Phase Key Terms
neural groove, notocord, neural crest, somites
Neural Groove
day 19 Gastrula Phase, develops in the neuroectoderm, cells start to grow together creating a tube with neural cells on outside and space on inside (spina bifida or encaphaly if skin doesn’t grow over)
Notocord
appears for short time in Gastrula Phase, sends out signals to cell layers in development
Neural Crest
Gastrula Phase, junction of neuroectoderm and ectoderm proper, sensory cells for the spinal cord
Somites
Gastrula Phase, these develop into peripheral nerves
Day 22.5 - so basically like 3 weeks and you are blissfully unaware
neural ectoderm has closed creating neural tube, mesoderm has separations for axial and appendicular skeleton, closure of neural tube starts in middle and moves towards ends (anterior/posterior neuropore), somites at top–>cranial nerves and spinal cord–>peripheral nerves
First Month of Fetal Development/Late Gastrula Phase 17-41 Days
(primary vesiscle stage) optic placode developing, ear placode, heart beat, aortic arches, limb buds from mesoderm
Neuronal Growth and Differentiation
- proliferation 2. migration 3. outgrowth of axons and dendrites 4. synapse formation and elimination 5. transneuronal influence 6. myelination
Proliferation Phase of Neuronal G&D
lots of mitotic action, more neurons made than those that live
Migration Phase of Neuronal G&D
cells born close to inner surface of neural tube and migrate out, throughout 9 months waves are created and sent out, when born all brain cells have been created (you are getting dumber as you read this)
Outgrowth of Axons and Dendrites Phase of Neuronal G&D
once cells are migrated the axons and dendrites grow out caused by chemical signals