Embryogenesis

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Author:
Aleksbaron
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270441
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Embryogenesis
Updated:
2014-04-17 20:15:43
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Exam III
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OBIO Exam III
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  1. At what week is the embryo become the fetus?
    8 weeks
  2. During the first two weeks of development the zygote is not susceptible to teratogens
  3. What is the most common birth defect?
    Cleft lip and palate
  4. Male sperm begin forming when?
    At puberty due to surge of LH and FSH
  5. In Meiosis how many cross over events occur?
    30-40, 1-2 per chromosome
  6. When do homologous pairs align in meisosis?
    During metaphase I
  7. When do primordial germs cells form in embryogenesis?
    During week 2, in epiblast and hypoblast

    4-6 weeks in polar body wall at gential ridge form the gonad
  8. How long is the process for male gametes?
    70-74 days
  9. What happens at puberty in males to start spermatogenesis?
    Leydig Cells are exposed to LH and in turn produce testosterone
  10. How early is egg formation in femals?
    Week 6 of embryo
  11. Describe oogenesis pre-puberty?
    mitosis produces many oogonium

    primary oocyte fetally undergo meiosis I and arrest at prophase

    female born with 400K-600K primary oocytes
  12. Describe oogenesis puberty?
    a primary oocytew undergoes oogenesis

    LH inc and leads to finish meiosis I, forming secondary oocyte and polar body

    then enters meiosis II and stops at metaphase II until fertilization
  13. Why does a polar body form in oogenesis?
    The cytoplasm from the polar body if robbed by the secondary oocyte to increase it's lifespan until implantation which does not occur for 2 weeks
  14. What does the follicle produces?
    Estrogen and progesterone
  15. describe folliculogensis pre-puberty?
    start as squamous cells
  16. describe folliculogeneiss at puberty?
    FSH stimulates 5-15 of primordial follicle to re-enter folliculogensis

    cells fatten and become cuboidal and begin produicing estrogen

    Zona Pellucida forms (glycoprotein layer) important until implantantion, not needed when implanting (can impede)

    follicular cells secrete lots of lfuid to fill antrum
  17. What cells produce estrogen?
    Granulosa cells
  18. What cells produce progesterone?
    Thecal cells
  19. What are the three phases of female reproductive cycle?
    • Luteal
    • Secretory
    • Menstrual or uterine
  20. What hormone dominates luteal phase?
    Progesterone
  21. How does birth control work?
    High P4 and High estrogen causes LH to stay low.
  22. What is the most common numerical chromosome abnormality?
    Trisomy caused by non-disjunction

  23. Trisomy 21
  24. Trisomy 18 
  25. Trisomy 13
  26. Klinefelters
  27. Turner Syndrome
  28. 47 XXX
  29. Cri-Du-Chat Syndrome
  30. Two microdeletion syndromes, name and describe?
  31. What is the embryo termed from 1-2 weeks?
    Morula (16 cells) or blastocyst
  32. What is the embryo termed week 2?
    Embryo, bilaminar disk
  33. What is capacitation?
    Sperm undergo breakdown of glycoprotein coat by  uterine secretions exposing receptors that allow to penetrate the egg
  34. What is the path of the egg from ovary to uterus?
    Ovary to abdominal cavity to infundibulum to ampulla to isthmus then to uterus
  35. Union of egg and sperm phases?
    • 1. Corona Radiata: penetration by capacitated sperm
    • 2. Zona Pellucida: penetrated by acromsomal rxn after binding of proteins sperm-egg
    • 3. Zona Reaction: enzymes release in egg hardens to prevent any other sperm, meisosis II finishes
  36. Zygote forms after sperm fertilizes egg and meiosis II finishes in egg
  37. What is the function of zona pelucida after fertilization?
    Limits growth of embryo allowing cells to be more condensed and have different contacts
  38. What cells form the placenta?
    The trophblasts or periphery cells
  39. End of second week the embryoblast has what two layers?
    Epiblast (dorsal) and hypoblast (ventral)
  40. What does the sphlanchnopleuric mesoderm give rise to?
    connective tissue that surrounds the umbilical cord
  41. What is the synctiotrophoblast responsible for?
    Lose cell membrane releasing enzymes that erode the uterus and produce HCG which allows P4 to continue to be produced
  42. When is uteroplacenta circulation established for nutrition of embryo?
    Day 12
  43. What does GIFT stand for?
    Gamete into Fallopian Tube
  44. What is a molar pregnancy?
    growth of placental material, secretes HcG, 1% of pregnancies, all trophoblastic cells

    5% of moles cause carcinoma
  45. When does the primitive streak form and the embryo is termed going through gastrulation?
    Beginning week 3
  46. At what areas of the embryo will you not find any mesoderm?
    Buccopharyngeal and cloacal membranes, ecto and endo derms approximate each other
  47. When does neuralation begin?
    Day 18
  48. What do neural crest cells differentiate into?
    sensory ganglia, ANS, and glial cells
  49. Ectoderm forms?
  50. Mesoderm forms?
  51. Endoderm forms?
  52. What is dextro cardia?
    Gastrulation defect, heart apex lies on the right side of the body
  53. What is situs inversus?
    Gastrulation defect can be complete or incomplete, organs are not where they should be, reveresed
  54. When the primitive streak does not regress at 4th week what can happen?
    sacrococcygeal terotoma may form, benign tumor
  55. When are organs done developing?
    by week 8, now fetal period where everything rapidly grows
  56. What is lanugo?
    fines hairs weeks 17-20 that cover fetus, degenerate before birth
  57. What is vernix caseosa?
    waxy cheese sebaceous fluid covering fetus weeks 17-20, antibacterial
  58. When do the testes decend from the posterior abdominal wall?
    Weeks 17-20
  59. When is surfactant begin to be produced?
    Weeks 21-25, by type II cells, sufficient surfactant is present week 28
  60. Blood formation and weeks 9-12?
    Shifts from liver to spleen
  61. Blood formation and weeks 26-29?
    shift from spleen to the bone marrow
  62. What are ways to monitor fetal development?
    • 1. Ultrasound: noticeable defects
    • 2. Maternal serum screens: downs syndrome
    • 3. Amniocentesis: diagnostic
    • 4. Chorionic villi sampling: diagnostic
  63. Weeks 30-35, significant changes?
    pupillary light reflex,

    testes reach scrotum, mine were at 2 weeks!
  64. Breathing and weeks 26-29?
    can occur under control of CNS
  65. When is the blink reflex present?
    Weeks 21-25
  66. When do bones begin to ossify?
    weeks 9-12

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