The Mouse

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  1. viviparous
    why does this cause problems?
    • embryo develops in uterus
    • problem because hard to examine embryos in utero
  2. Fertilization
    • sperm released into female
    • capacitation period
    • sperm gets to egg and has hyaluronidase that gets them through the cumulus-matrix complex
    • ZP3 in zona pellucida recognizes sperm by binding GalT on sperm
    • exocytosis of acrosome releases acrosin: a serine-protease that digests a path through zona pellucida so sperm can reach the egg
    • sperm reaches the egg
    • ADAM proteins on sperm bind to integrins on egg
    • the 2 membranes fuse by CD9 on egg and GPI-anchored cell surface proteins
    • fusion happens and whole sperm enters egg
  3. polyspermy
    fertilization by multiple sperm
  4. acrosome
    • structure at front of sperm cell
    • important for fertilization
    • filled with serine protease (acrosin) that digests a path through zona pellucida
  5. capacitation
    • process that makes the sperm competent to fertilize egg
    • happens in female reproductive tract
    • can be done in vitro with albumin/calcium/bicarbonate solution that activates adenylyl cyclase which increases cAMP and activates protein kinase A = increase in membrane potential, pH, calcium, and motility
  6. egg
    • oocyte arrested at metaphase II
    • surrounded by follicle cells (cumulus cells)
    • zona pellucida which is extracellular material
  7. zona pellucida
    • has special proteins: ZP1, ZP2, ZP3
    • ZP3: sperm binds to this, recognizes sperm from same species only
  8. egg activation
    • after the plasma membranes of the egg and sperm fuse, intracellular calcium concentration increases
    • this increase in calcium is a universal response in animals
    • calcium transients: calcium concentration fluctuates
    • sets in motion many events:
    • cortical granules are released and modify zona proteins so they can't bind sperm anymore
    • meiotic division completes: 2nd polar body is extruded, sperm nucleus decondenses, pronuclei migrate to each other, DNA replication occurs, chromosomes align for first mitotic division
  9. where do centrioles come from?
    • in mouse: both come from oocyte
    • in most mammals: sperm contributes centriole that becomes microtubule organizing center
  10. preimplantation stages
    • fertilization in oviduct
    • slow cleavage divisions: 12-24 hours per division
    • divisions not synchronous
    • rotational cleavage
    • 8 cell stage: compaction
    • 16 cell stage: morula
  11. rotational cleavage
    • first cleavage meridional
    • second cleavage: one cell meridional, one cell equatorial
  12. compaction
    • at 8 cell stage
    • cells express E-cadherin and form tight associations with each other
    • these cells are totipotent
  13. pluripotent
    able to form all the cells of the body but not extraembryonic tissues
  14. totipotent
    each cell can form an entire embryo including extraembryonic tissues
  15. 16 cell stage
    • morula
    • inner cell mass surrounded by trophectoderm
    • outer cells pump sodium into morula so water follows = forms blastocoel (cavity)
  16. inner cell mass
    • will form the embryo
    • pluripotent
    • express Oct4
    • if express Nanog will form epiblast because Nanog suppresses hypoblast fate and promotes epiblast fate
  17. trophectoderm
    • outer cells surrounding inner cell mass
    • will form the trophoblast which will make the chorion
  18. Cdx2
    • expressed by trophoblast cells
    • suppresses the expression of the transcription factors Oct4 and Nanog
  19. Nanog
    • suppressed hypoblast fate and promotes epiblast fate
    • essential for ES cell identity and pluripotency
  20. Oct4
    • expressed in ICM
    • essential for ES cell identity and pluripotency
  21. GATA4
    • express this if don't express Nanog
    • will form hypoblast
  22. Early post-implantation
    • embryo hatches from zona and implants in uterine wall
    • trophoblast proliferates and stimulates proliferation of uterine mucosa (uterine wall) = diciduum formation
    • nutrients transported to embryo from mother and growth begins
    • egg cylinder stage
    • E6.5: primitive streak forms
    • E7.5: head process forms anterior to the node
    • E8: somites begin to form
    • mesoderm and extraembryonic ectoderm grow out to form amnion and chorion
    • embryo turning
  23. egg cylinder stage
    • epiblast forms embryo proper
    • hypoblast = primitive endoderm
    • visceral endoderm: important extraembryonic tissue
  24. E6.5
    • Primitive streak: region of convergence and invagination of cells in a gastrulating amniote embryo,¬†marks posterior end. ¬†cell movement similar to birds = formation of mesoderm and endoderm
    • node forms at anterior end: like fish shield, xenopus dorsal lip, Hensen's node in birds
  25. E7.5
    head process forms anterior to node: forming notochord, neural plate
  26. E8
    somites begin to form
  27. mesoderm and extraembryonic ectoderm grow out to form amnion and chorion
    • amnion: extraembryonic tissue that surrounds the embryo
    • chorion: extraembryonic tissue that forms the placenta
    • allantois: formed by extraembryonic mesoderm, grows and contacts chorion, forms embryonic blood vessels and placenta
    • placenta: forms from ectoplacental cone
  28. embryo turning
    • embryo flips around about its long axis
    • this moves the endoderm/mesoderm to facing inside and ectoderm facing the outside
    • only happens in rodents
Card Set:
The Mouse
2013-10-30 06:37:10
Developmental Biology

test 2
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