1. Fertilization!

2. “The elements that unite are single cells, each on the point of death; but by their union a rejuvenated individual is formed, which constitutes a link in the eternal process of Life.” ~ F. R. Lillie

3. Union of Sperm and Egg

4. Union of Egg and Sperm Oviduct Can only occur directly after egg ovulated

5. How many sperm fertilize egg? Survival of the fittest Polyspermy– nondisjunction? ??? Blocks to polyspermy http://www.molbiolcell.org/content/vol9/issue7/images/video/mk0780641001. mov

7. Slow Block to Polyspermy– formation of fertilization envelope http://www.molbiolcell.org/content/vol9/issue7/ima ges/video/mk0780641001.mov

8. Thought Question What is the problem with 2+ sperm fertilizing one egg? How is this problem related to nondisjunction?

9. Twins/IVF

10. Twins Zygote = fertilized egg

12. When fertilized egg splits partially

13. In Vitro Fertilization In Vitro= in petri dish Egg + sperm united outside body

14. Thought Question What potential fertility problems (M and F)may lead couples to engage in IVF?? Why?? Think of at least 2!!!

15. IVF often leads to multiple births Multiple zygotes implanted Increased likelihood for complications

17. How Often Fertilization Works

18. “If you think it’s amazing that any one of us survives to be born, you are correct.”~ Gilbert, Developmental Biology

19. Thought Question Out of 20 hypothetical human eggs that come into contact with sperm, how many lead to: – Successful fertilization – Successful implantation – Successful development, 4 th week – Successful development, 8 th week – Fetuses coming to term – OVERALL, what percentage of human conceptions successfully come to term?

20. ½ to 2/3 of human conceptions don’t come to term

21. Implantation in Uterus/Nourishment for Baby

22. Implantation in Uterus

23. Ectopic Pregnancy

24. Umbilical Cord and Placenta

25. Amniotic Fluid

26. Contraception

27. Physical Barrier methods

28. Chemical Methods

29. Thought Question A woman taking birth control still receives her period. What must necessarily occur for this to happen? New birth control pills have been developed that allow women only to get their periods a few times a year. What must be different about these pills vs. normal birth control?

30. Figure 46.21 Mechanisms of some contraceptive methods