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  1. when is the embryonic period?
    fertilization > 8th week
  2. When is the fetal period?
    9th week > birth
  3. What is the most critical stage of development?
    first trimester?
  4. When does the initial appearanc eof all major organ systems occur?
    first trimester?
  5. when is the fetus most vulnerable to effects of drugs, radiation, and microbes?
    first trimester?
  6. Which trimester is the fetus nearly completed development of organ systems?
  7. which trimester has the most rapid fetal growth?
  8. What does the sperm penetrate during fertilization?
    • corona radiata
    • zona pellucida
  9. What does the sperm bind to during fertilization?
    zona pellucida
  10. what happens when the sex cell's membranes fuse?
    • oocyte completes meiosis and divides
    • pronuclei form and fuses
    • results in a zygote
  11. how many cells is in a zygote?
    2 > 4 > 8
  12. what is a morulla?
    zygote with 16 cells in it
  13. what happens in the first week of development?
    • blastocyst formation from the morula
    • ---inner mass becomes embryoblast
    • --- outer wall is trophoblast
  14. where does the zygote implant during the first week?
    • fundus or body of uterus
    • blastocyst attaches to endometrium
  15. what happens during the second week of development?
    • trophoblast develops into 2 laters
    • embryoblast develops into bilaminar embryonic disk
  16. what are the 2 layers of trophoblast(Chorion) in the second week?
    • syncytiotrophoblast
    • cytotrophoblast
  17. what forms in the hypoblast?
    yolk sac
  18. what forms where the epiblast is?
    amniotic cavity
  19. What happens during the third week of development?
    gastrulation produces trilaminar embyonic disc
  20. what are the 3 primary germ layers that form during the third week of development?
    • ectoderm
    • endoderm
    • mesoderm
  21. what does ectoderm later become?
    epidermis of skin, nervous system
  22. where does endoderm later become?
    • epithelial linings of GI tract,
    • respiratory tract,
    • urinary tract,
    • and many glands
  23. Whhere does the mesoderm form?
    between ectoderm and endoderm
  24. what doest he mesoderm later become?
    muscles, bones, C.T, peritoneum
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2013-12-11 08:35:33
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