development mini1b

  1. phases of spermatognesis
    • 1. spermatogonial- spermatogonia differentiate into primary spermatocytes (2n)
    • 2. spermatocyte- meiosis 1 and 2 (4n then 2n)
    • 3. spermiogenesis- spermatids differentiate into spermatozoa (1n)
  2. oocyte development
    before birth primary oocytes enter 1st stage of meiosis and are arrested in DIPLOTENE stage by OMM released by follicular cells
  3. oogonia numbers
    • 5 mts- 7 million oogonia
    • birth- 600,000 to 2 million
    • buperty- 400,000
  4. usual site of fertiliztion
    ampullary region of fallopian tube
  5. stages of oocyte development
    • primary- 4n
    • secondary- 2n + 1 polar body
    • mature- 1n + 3 polar bodies
  6. preovulatory follicle
    • releases egg to infundibulum, then if egg is fertilized, will turn into the CORPUS LUTEUM which maintains hormone release
    • -if no fertilization with shrivel into CORPUS ALBICANS.
  7. capacitation
    • *sperm passes thru corona radiata*
    • removal of glycoprotein and cholesterol coat of sperm (prevents zona pellucida binding) by the uterus and fallopian tube so they can penetrate the corona radiata
  8. acrosomal reaction
    • *sperm penetrate the zona pellucida*
    • -hyalauronidase, acrosin are main enzymes
  9. steps of fertilization
    • 1-capacitation(corona radiata penetration)
    • 2-acrosomal reaction(zona pellucida penetration)
    • 3- spermatazoa fuses with the 2 oocyte PM
    • 4-fastblock- depol of PM to prevent other sperm bind
    • 5-slowblock(cortical rxn)- causes high Ca stores to cause release of cortical granules
    • 6-zonal rxn- ez from granules alter PMr and zona pellucida
    • 7- polyspermia prevented and 2 oocyte completes meiosis 2 to yield ovum and 2nd polar body
    • 8- formation of female PRONUCLEUS
    • 9-male PRONUCLEUS formation
    • 10-pronuclei fusion, fertilization complete, ZYGOTE produced
  10. cleavage divisions
    rapid mitotic divisions in which the cells DO NOT grow in size. first occurs 30 hours after the beginning of fertilization
  11. most critical time of development
    weeks 3-8
  12. morula
    • -about 12-16 cell ball
    • -forms at about 3 days
    • - as cleavage continues morula passes down FT towards the uterus
  13. blastocyst
    • day 4-embryo enters uterine cavity
    • - inner cells (embryoblast) become the embryo proper
    • -outer cells (trophoblast) form part of the placenta
    • embryoblast+ trophoblast= blastocyst
    • -blastocyst in uterine for 2 days as zona pellucia disapears
  14. day 6
    begin penetration of trophoblast thru uterine epithelium toward uterine stroma
  15. summarize week one (5)
    • 1- ovulation
    • 2- fertilization
    • 3- cleavage, morula, blastocyst
    • 4- zona pellucida disappearance
    • 5- trophobladst invades superficial epithelia
  16. day 7-8
    -epiblast formation (columnar) + hypoblast formation (cuboidal)= BILAMINAR GERM DISC

    trophpblast divison = syncitiotrophoblast and cytotrophoblast
  17. amnion formation
    • day 8
    • small cavity appears within the epiblast becoming amniotic cavity, cells lining the cavity are amnioblasts, which form the amnion
  18. day 9-10
    • embyro completely embedded in uterine endometrium and fibrin plug closes gap
    • *embryo seperated from cytotrophoblast above by amnotic cavity and below by th primitive yolk sac
  19. heusers membrane
    line primitive yolk sac
  20. day 11-12
    • -uterine epithelium is relining where penetrated
    • -maternal sinusoids fuse with syncitiotrophoblastic lacuna, establishing uteroplacental circulation
    • -mesenchyme formation
    • -chorionic cavity formation from extraembryonic mesoderm
  21. day 13
    secondary yolk sac formtion

    -primary stem villi formation by cytotrophoblast cells
  22. conneting stalk
    • forms around day 13 and will form part of the umbilical cord
    • -only place where extraembryonic mesoderm traverses the chorionic cavity (an expansion of the extraembryonic coelom)
  23. day 14
    oropharygeal plate and oropharyngeal membrane formation
  24. week 2 summary (7)
    • 1-trophoblast differentiation
    • 2-lacunar network formation=> uteroplacental circ formation
    • 3-primary chorionic villi
    • 4-implantation completion
    • 5-amnion and 2 yolk sac formation
    • 6-bilamina germ disc formation
    • 7-oropharyngeal plae development
  25. placental previa
    implantation of blastocyst into the internal os, leads to severe bleeding during birth
  26. prevention of maternal rejection of embryo
    • 1- cytokines like IL-2
    • 2- MHC-1B (HLA-G)
  27. gastrulation
    • -happens 3rd week
    • 1- primitive streak formation
    • 2- triaminar formation
    • 3-notocord formation
  28. germ layer formation
    • epiblast cells migrate to primitive streak and slip under (with direction of FGF) and will form endoderm, mesoderm and ectoderm
    • -axis also developes
  29. notocord formation
    • epiblast cells migrate thru primitive pit toward oropharyngeal plate and form notocord(mesodermal cells)
    • **essential for neural tube deelopment**
  30. prechordal plate
    essential for forbrain development
  31. mesoderm cells dont migrate here
    where cloacal and orophayngeal membranes form
  32. cardiogenic area
    in front of prechordal plate where mesodermal cells will give rise to the heart
  33. allantois formation
    • day 16
    • -early blood formation and urinary bladder
    • -vessels become the umbilical a. and v.
    • -will become the median umbilical ligament in adults
  34. primitive streak disappearance
    end of 4th week
  35. paraxial mesodermal fate
  36. intermediate mesoderm fate
    urgenital system
  37. lateral plate mesoderm fate
    muscles and divides body cavities
  38. these organs start on the left side of the body
    heart, lungs, stomach, gut and spleen
  39. complete situs inversus
    inversion of all internal organs to opposite side
  40. SHH
    • sonic hedgehog
    • produced by primitive node and is invilved in midline formation
  41. sacrococcygeal teratoma
    tumor that arises from primitive streak that does not degenerate when it should (end of the 4th week)
  42. sirenomelia
    • associated with maternal diabetes
    • -not enough mesodem migrates to lateral plate mesoderm and causes fusion of limb buds and other defects
  43. notocord appearance
    • week 3
    • -mesodermal origin
    • -induces ectoderm to thicken and form neural plate
  44. fusion of neural groove
    occurs at the 5th somite and result in formation of neural tube
  45. neural crest cells
    crest of the wave of neural tube formation and will detach when neural tube closes and become the spinal ganglion
  46. ectoderm fate after neural tube formation
  47. BMP-4
    • - causes ectoderm--> epidermis
    • - mesoderm--> lateral plate and intermed. mesoderm
    • -**inactivation causes neural plate induction**
  48. closure of neuropores
    cranial at day 25-26

    • caudal at 27-28
    • **signal completion of neuralation, and ventricule and spinal cord formation begins**
  49. lens placode
    • 5th week
    • forms the lens of the eye
  50. telencephalon
    gives rise to 2 cerebral hemispheres
  51. ectoderm derivatives
    • CNS, PNS, sensory epithelim, epidermis, anterior pituitary, enamal, derivatives of neural crest cells
    • (contact with the external world)
  52. somites
    • form from paraxial mesoderm
    • 42-44 pairs by the 35th day
    • -differentiation occurs by start of the 4th week
  53. sclerotome
    somite cells that differentiate into vertabra and ribs
  54. myotomes and dermatomes
    retain innervation from segment of origin regardless of migration
  55. body cavitiy formation
    by 8th week intraembryonic cavity gives rise to peritoneal, plearal and pericardial cavities
  56. blood formation and vessel formation
    • starts in yolk sac and allantois, then liver, then bone marrow
    • -vasculogenesis- vessels arise from blood islands
    • -angiogenesis- vessels arise from existing vessels
  57. heart formation
    • day 21
    • heart tubes fuse into single tube that starts to beat
  58. mesoderm derivatives
    adrenal cortex, spleen, CT, cartilage, bone, blood, urogenital, serous membranes lining body cavities
  59. septum transversum
    forms part of diaphragm
  60. gastroschisis
    anterior abdominal wall defect(lateral folding failure) that results in visceral organs outside of the body
  61. epithelial to mesenchymal transformation
    neural cells undergo this process after neural tube formation, then migrate to the underlying mesoderm
  62. neural crest cell differentiation, 3 types
    • first- can be several different types
    • later- only dorsal derivitives
    • last- pigment cells
  63. neural crest derivatives
    bones of face and skull, adrenal medulla,glial cells, odontoblasts, septum of heart, thyroid c cells (calcitonin)
  64. sympathetic neurons
    form from NC cells in the trunk region
  65. parasympathetic neurons
    form from NC cells in the cranial region
  66. trunk NC migrations
    • 1-ventrolaterally- DRG
    • 2-ventrally- adrenal medulla and SNS
    • 3- dorsolaterally-melanocytes
  67. circumpharyngeal neural crest migrations
    • 1-enteric crest-PSN of gut
    • 2-cardiac crest cells- large ateries and aorticopulmonary septum
    • 3- pharyngeal arches
  68. cardiac crest cell disturbances
    • 1-cardiac septum defects
    • 2-DiGeorge syndrome- reduced function of thymus, thyroid and parathyroids
  69. cranial neural crest cells migration
    • *starts before closure of neural folds*
    • -midbrain-r2= paryngeal arch->jawbone, facial bones, incus and maleus
    • -r4-phar. arch 2=hyoid carltilage and stapes
    • -r6-r7= 3rd PA to form lower hyoid bone
  70. hirschsprungs disease
    aganglionic megacolon
  71. chorionic gonadotropin
    • secreted by sycitiatrophoblast to tell ovary to retain the corpus luteum which will continue to secrete progesterone and keep endometrial functional layer of uterus
    • *hormone for prego testing*
Card Set
development mini1b
development mini1b