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Lecture 16: Fertilization

Lecture 16: Fertilization. Animal Science 434 John J. Parrish. Capacitation. 1951 Austin - rat Chang - rabbit Fertilization does not occur until several hours after sperm are placed in the uterus or oviduct. Chang Experiment - 1951. Ovulation. After. Before. Percent Fertilization.

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Lecture 16: Fertilization

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  1. Lecture 16: Fertilization Animal Science 434 John J. Parrish

  2. Capacitation • 1951 • Austin - rat • Chang - rabbit • Fertilization does not occur until several hours after sperm are placed in the uterus or oviduct

  3. Chang Experiment - 1951 Ovulation After Before Percent Fertilization

  4. Capacitation The changes within sperm that confer upon the sperm the ability to acrosome react in response to the appropriate stimulus. • Zona Pellucida • Cumulus Cells • Follicular Fluid

  5. Epididymal Ejaculated Capacitated Seminal Plasma Female Tract + + Effect of Capacitation

  6. Model of Capacitation D F Acrosome Nucleus Cytoplasm Plasma Membrane

  7. Chol-Acceptor GAG D D D D D F F F F F Ca2+ pH Activity of Enzymes cAMP Ca2+ Cholesterol Acrosome Nucleus Cytoplasm Plasma Membrane

  8. Capacitation • No change in sperm morphology • Motility change • hyperactivation cAMP Power output

  9. Fused Plasma Membrane and Outer Acrosomal Membrane Acrosin Hyaluronidase The Acrosome Reaction Plasma Membrane Acrosome Nucleus

  10. Modification of the Equitorial Region

  11. The Zona Pellucida ZP1 ZP2 ZP3

  12. Sperm Interaction with the Zona Attachment Zona Pellucida Binding ZP3 Acrosome Reaction Induction Acrosome Reaction

  13. ZP2 ZP2 ZP2 ZP2 Secondary Binding Zona Pellucida Zona Penetration Motility

  14. Zona Pellucida

  15. Sperm tract through zona pellucida

  16. 6-12 hr 18-24 hr

  17. MPF MPF MPF MPF Maturation Promoting Factor(MPF) LH Surge Metaphase Promoting Factor Primary Oocyte GVBD Metaphase I GV-Intact PB-1 Ovulation Metaphase II Secondary Oocyte

  18. Ca2+ Ca2+ Ca2+ Ca2+ Zona Pellucida Oocyte Perivitelline Space

  19. Calcium Transients During Bovine Fertilization

  20. Initiation of Calcium Pulse by Soluble Sperm Component

  21. Calcium Pulse Initiated by IP3 Ca++ IP3 ER

  22. Pronuclei Ca2+ AII X TII MII PBII Zona Pellucida Oocyte MPF Perivitelline Space

  23. Decondensation Pronuclei Pronuclei Ca2+ AII X TII MPF MII PBII Zona Pellucida Oocyte Zygote Perivitelline Space

  24. Ca2+ Cortical Granules Zona Pellucida Oocyte Zona Block to Polyspermy Perivitelline Space

  25. Blocks to Polyspermy Species 1. Mammals 3. InvertebratesAmphibiansFishRabbits 4. AmphibiansAvians 1 2 3 4

  26. Sperm acrosomal region binds to sperm receptor on zona Perivitelline Space Initiates completion of Meiosis II and release of 2nd polar body 1st Polar Body Vitelline Membrane Zona Pellucida Initiates - Zona & Vitelline Reaction Cortical Granule ZP3 Binding Fusion Cortical Granule Release Zona Reaction Initiation of Acrosome Reaction Excluded Sperm Continuation of Reaction Acrosome-Reacted Sperm Penetration Zona and Vitelline Reactions block polyspermy Sperm penetrates zona Redrawn from Wasserman, P.M. 1988 Scientific American. p78

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